METHOD OF REMANUFACTURING SCRAPER CONVEYOR TECHNICAL FIELD The present disclosure mainly relates to the technical field of machine 5 manufacturing, and more particularly to a method of remanufacturing a scraper conveyor. BACKGROUND Any discussion of the background art throughout the specification should in 10 no way be considered as an admission that such background art is prior art nor that such background art is widely known or forms part of the common general knowledge in the field in Australia or worldwide. As a crucial part of underground fully-mechanized coal-mining equipment, a scraper conveyor is mainly used to transport coal, support a shearer to walk and 15 move hydraulic supports on working face. During use, a middle plate, a base plate, a scraper, both sides of a chain track and two-side plates of a headstock of the scraper conveyor are worn quite seriously and the strength is decreased, because of the friction between the scrapers and them, so that the scraper conveyor is unable to transport coal, support the shearer to walk and move 20 hydraulic supports, which is the major reason for scraper conveyors' failure. The traditional countermeasure of scraper conveyor's wear failure is to replace components and parts, the worn middle plate, the base plate, the middle chute and two-side plates of the headstock are separately replaced with a corresponding new one, and the seriously worn parts will be scraped. At present, 25 the repair of worn scraper conveyors inland and abroad are only limited to an ordinary welding repairing technology and the repairing quality is quite poor, which cannot reuse the worn channel ledge steel, the middle plate or the base plate and cannot achieve the residual life value. There is no standard for remanufacturing scraper conveyors inland and abroad, all major coal mines will scrap scraper 1 conveyors because of the ultimate wear failure of most middle plates and base plates, and only repair a very small amount of lightly worn ones, rather than remanufacture them, which causes great waste of materials and serious environment pollution. Thus, it is an urgent technical problem for technicians that 5 how to repair worn components of the scraper conveyors effectively up to the technical standards before use. SUMMARY Throughout this specification, unless the context requires otherwise, the 10 words "comprise", "comprises" and "comprising" will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements. Any one of the terms: "including" or "which includes" or "that includes" as used herein is also an open term that also means including at least the 15 elements/features that follow the term, but not excluding others. Thus, "including" is synonymous with and means "comprising". It is an object of the present invention to overcome or ameliorate at least one or more of the disadvantages of the prior art, or to provide a useful alternative. Against the defects and deficiencies of the existing method, the present 20 disclosure accordingly provides a method of remanufacturing a scraper conveyor with low cost, high repairing efficiency and reliable technical effect, which can repair a worn middle chute, a middle plate, a base plate, two side plates of the chain track and two side plates of the headstock of the conveyor to make their wear resistance up to or better than the wear resistance of the original mechanical properties, so as 25 to achieve the remanufacturing of the scraper conveyor in a real sense. In order to reach the above aim, the present disclosure accordingly provides a method of remanufacturing a scraper conveyor, which includes the following steps: Measure the wear loss of each part of a worn scraper conveyor; perform 2 remanufacturing according to the condition of wear loss; wherein the remanufacturing includes repairing and/or replacing; the process of the repairing is surfacing welding. Further, before measuring the wear loss of each part of the worn scraper, the 5 method further includes: remove pollutant from the surface and a surface layer of each part. Further, the method further includes: perform weld inspection, and a process of the weld inspection is visual inspection, magnetic particle inspection or X-ray inspection. 10 Further, the method further includes: repair the weld with a crack defect after weld inspection, wherein the process of repairing includes: perform air gouging on the weld with a crack; grind two sides of the weld to expose the metallic luster; reweld the weld with an ordinary welding wire or an ordinary welding rod. 15 Further, the standard and the process of repairing according to the wear loss include: (1) Compare with a new product, when the wear loss of the middle plate or the base plate is less than or equal to 10% of a new product, directly perform surfacing welding with a first wear strip or a first wear block by using a wear welding wire or 20 wear welding rod; when the wear loss is more than 10% of a new product and less than 30% of a new product, firstly perform backing welding with the ordinary welding wire or the ordinary welding rod, and then perform surfacing welding with the first wear strip or the first wear block by using a wear welding wire or wear welding rod; (2) When the wear loss of the middle plate or the base plate is less than or 25 equal to 30% of a new product, wherein there are no more than three worn parts of which the wear loss is more than 30% of a new product and less than or equal to 3 50% of a new product, firstly perform backing welding with the ordinary welding wire or the ordinary welding rod, and then perform surfacing welding with the first wear strip or the first wear block by using the wear welding wire or the wear welding rod; (3) When the wear loss of the width of a monolateral chain track of channel 5 ledge steel is less than or equal to 23% of a new product, and the wear loss of the inside height of the chain track is less than or equal to 8% of a new product, perform surfacing welding with a second wear strip or a second wear block by using the wear welding wire or the wear welding rod; When the wear loss of the width of the monolateral chain track of the channel 10 ledge steel is more than 23% of a new product and less than or equal to 33% of a new product, and the wear loss of the inside height of the chain track is more than 8% of a new product and less than or equal to 10% of a new product, cover the entire inside wall of the chain track of the channel ledge steel with a plate, wherein the thickness of the covering plate is half of the wear loss of the inside height of the 15 chain track; (4) When the wear loss of two side plates of the headstock is less than or equal to 10% of a new product, directly perform surfacing welding with the first wear strip by using the wear welding wire or the wear welding rod; when the wear loss of two side plates is more than 10% of a new product and less than 30% of a new product, 20 firstly perform backing welding by using the ordinary welding wire or the ordinary welding rod, and then perform surfacing welding with the first wear strip by using the wear welding wire or the wear welding rod. Further, when the wear loss of a middle plate or a base plate is more than 30% of a new product, replace the middle plate or the base plate. 25 When the wear loss of the connection end of a middle plate or a base plate is more than 30% of a new product, the wear loss of other parts is less than or equal to 30% of a new product, replace the worn connection end with a new one and repair other parts. 4 When the wear loss of the width of a monolateral chain track of channel ledge steel is more than 33% of a new product, and/or the wear loss of the inside height of the chain track is more than 10% of a new product, replace it. When the wear loss of two side plates of a headstock is more than 30% of a 5 new product, replace them. Further, the ordinary welding wire is GHS-60 welding wire, the ordinary welding rod is E5015/E5016 welding rod; preheat the workpiece to 80 -150 before performing the backing welding with the ordinary welding wire or the ordinary welding rod. 10 The wear welding wire is Castolin wear welding wire, and the wear welding rod is Castolin wear welding rod; preheat the workpiece to 200 -230 before performing the surfacing welding with the wear welding wire or the wear welding rod. Further, while performing the surfacing welding to repair workpieces, 15 intermittent surfacing welding is adopted, and the process of intermittent surfacing welding includes: firstly perform intermittent surfacing welding with an interval distance of 150-300mm, and then perform surfacing welding on the intervals to complete the weld. Further, the first wear strips locate at the planes of the middle plate and the 20 base plate; the first wear blocks locate at a connection end of the middle plate and a connection end of the base plate and just under the chains, the amount and interval distance of weld match with the chains; the second wear strips locate in the chain-track inside of the channel ledge steel, and the second wear blocks locate at a connection end of the channel ledge steel. 25 This present disclosure has these advantages as below: 1. In this present disclosure, easy worn positions of the channel ledge steel, the middle plate, the base plate, two sides of the chain track and two-side plates of 5 headstock in middle chute are targetedly repaired and replaced, which can increase the utilization ratio of components and parts, reduce the waste of resources and prolong service life of equipment. 2. In this present disclosure, the process of surfacing welding with the wear 5 strip adopts intermittent welding, which can prevent the repaired parts from deformation caused by weld thermal stress, and improve repairing accuracy. 3. In this present disclosure, inspect the connection positions of the crucial parts by visual inspection, magnetic particle inspection or X-ray inspection, and repair the weld with a crack, which can exclude the damage hidden-trouble of parts 10 effectively, and guarantee the remanufacture quality. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic structural view of a middle chute of the present 15 disclosure; and Fig. 2 is a schematic structural view of a headstock of the present disclosure. 1-channel ledge steel, 13-chain track, 11-connection end of channel ledge steel, 12-monolateral chain track, 2-middle plate, 21-connection end of middle 20 plate, 3-base plate, 31-connection end of base plate, 4-headstock, 41-side plate. DETAILED DESCRIPTION In order to make the skilled in this art understand the present disclosure better, the present disclosure will now be described more clearly and fully hereinafter. 25 According to the exemplary embodiments of this disclosure, all other similar embodiments obtained by those skilled in this art without any creative work belong to the protection scope of the present disclosure. 6 Embodiment One: A method of remanufacturing a scraper conveyor is provided, which includes the following steps: Perform non-chemical cleaning on mechanical-body components of a worn 5 scraper conveyor using high pressure water and shot blasting cleaning technologies to remove the pollutant on the surface and the surface layer of the components and parts, and remove the oxide, carbon deposits, oil and other pollutant on the surface of the parts using the technologies of soft abrasive blast cleaning, shot blasting and high-pressure water jet cleaning and so on, so as to 10 expose their metallic luster; perform measurement after cleaning. Visual inspection, magnetic particle inspection or X-ray inspection are adopted to inspect the weld and mark the weld with crack defect. Perform air gouging on the marked weld with crack, and then grind two sides of the weld to expose the metallic luster; 15 Reweld the weld with an ordinary welding wire or an ordinary welding rod, the ordinary welding wire is GHS-60 welding wire, and the ordinary welding rod is E5015/E5016 welding rod; the welding process of the ordinary welding wire is C02 shielded arc welding, and the welding process of the ordinary welding rod is shielded metal arc welding. During the underground work, the weld is rewelded by 20 shielded metal arc welding with E5015/E5016 welding rod in the narrow space; during the ground work, C02 shielded arc welding is adopted. The welding process of C02 shielded arc welding includes: the shielding gas is mixed gas of Ar and C02 with a mixture rate of 4:1, the gas flow is 15-20L/min, the diameter of the selected welding wire is <b 1.6mm; metal transfer adopts spray transfer; the 25 parameters of the current and the voltage are 280-300A and 30-32V respectively; the heat input is controlled under 20kJ/cm; the welding speed is controlled at 200-220mm/min. The welding parameter of the welding rod E5015/E5016 is as 7 follows: the welding current is 90-150A, and the welding speed is 120-150mm/min. As shown in Fig. 1 and Fig. 2, a metal thickness detector is adopted to measure the wear loss respectively, and the standard and the process of repairing include: 5 (1) Compare with a new product, when the wear loss of the middle plate 2 or the base plate 3 is less than or equal to 10% of a new product, perform surfacing welding with a first wear strip or a first wear block by using a wear welding wire or a wear welding rod; when the wear loss is more than 10% of the new product and less than 30% of a new product, firstly perform backing welding with an ordinary 10 welding wire or an ordinary welding rod, and then perform surfacing welding with a first wear strip or a first wear block by using a wear welding wire or a wear welding rod. (2) When the wear loss of the middle plate 2 or the base plate 3 is less than or equal to 30% of a new product, wherein there are no more than three worn positions 15 of which the wear loss is more than 30% of a new product and less than or equal to 50% of a new product, firstly perform backing welding with ordinary welding wire or the ordinary welding rod, and then perform surfacing welding with the first wear strip or the first wear block by using the wear welding wire or the wear welding rod. (3) When the wear loss of the width of a monolateral chain track of channel 20 ledge steel 1 is less than or equal to 23% of a new product, and the wear loss of the inside height of the chain track is less than or equal to 8% of a new product, perform surfacing welding with a second wear strip or a second wear block by using the wear welding wire or the wear welding rod. When the wear loss of the width of the monolateral chain track of the channel 25 ledge steel 1 is more than 23% of a new product and less than or equal to 33% of a new product, and the wear loss of the inside height of the chain track is more than 8% of a new product and less than or equal to 10% of a new product, cover the entire inside wall of the chain track of the channel ledge steel with a plate, wherein 8 the thickness of the covering plate is half of the wear loss of the inside height of the chain track. (4) When the wear loss of two side plates 41 of the headstock 4 is less than or equal to 10% of a new product, directly perform surfacing welding with the first wear 5 strip by using the wear welding wire or the wear welding rod; when the wear loss of two side plates is more than 10% of a new product and less than 30% of a new product, firstly perform backing welding with the ordinary welding wire or the ordinary welding rod, and then perform surfacing welding with the first wear strip by using the wear welding wire or the wear welding rod. 10 Further, when the wear loss of middle plate 2 or the base plate 3 is more than 30% of a new product, replace the middle plate2 or the base plate 3; When the wear loss of the connection end of the middle plate 2 or the connection end of the base plate 3 is more than 30% of a new product, and the wear loss of other parts is less than or equal to 30% of a new product, replace the 15 worn connection ends of the middle plate 2 or the base plate 3 with new ones, and repair other parts. When the wear loss of the width of a monolateral chain track of the channel ledge steel 1 is more than 33% of a new product, and/or the wear loss of the inside height of the chain track is more than 10% of a new product, replace it. 20 When the wear loss of two side plates 41 of a headstock 4 is more than 30% of a new product, replace them. The wear welding wire is Castolin wear welding wire; the welding process of Castolin wear welding wire is C02 shielded arc welding; the shielding gas is a mixed gas of Ar and C02 with a mixture rate of 4:1; the gas flow is 17L/min; the 25 diameter of the selected welding wire is <b 1.6mm; the metal transfer adopts spray transfer; the parameters of the current and the voltage are 270-325A and 27-31V respectively; the heat input is controlled under 20Kj/cm; the welding speed is 9 controlled at 280-340mm/min; the preheat temperature is 200-230 before welding. The ordinary welding wire is GHS-60 welding wire; the welding process of backing surfacing with the ordinary welding wire is C02 shielded arc welding; the 5 shielding gas is a mixed gas of Ar and C02 with a mixture rate of 4:1; the gas flow is 17L/min; the diameter of the selected welding wire is <b 1.6mm; the metal transfer adopts spray transfer; the parameters of the current and the voltage are 280-300A and 30-32V respectively; the heat input is controlled under 20Kj/cm; the welding speed is controlled at 200-220mm/min. 10 The wear welding rod is Castolin welding rod; the welding process of Castolin welding rod is shielded metal arc welding; wherein the welding current is 240-260A, and the welding speed is controlled at 140-160mm/min. The ordinary welding rod is E5015/E5016 welding rod; the welding process of the ordinary welding rod is shielded metal arc welding; wherein the welding 15 current is 90-150A, and the welding speed is controlled at 120-150mm/min. Before performing the backing welding with the ordinary welding wire or the ordinary welding rod, preheat the parts to 80 -150 . Before performing the surfacing welding with the wear welding wire or the wear welding rod, preheat the parts to 200 -230 . 20 While performing surfacing welding to repair workpieces, the intermittent surfacing welding is adopted, and the process of the intermittent surfacing welding includes: firstly perform the intermittent surfacing welding with an interval distance of 150-300mm, and then perform surfacing welding on the intervals to complete the weld. 25 Perform anticorrosion treatment after repairing the parts, and the anticorrosion treatment is painting. Embodiment Two: 10 As shown in Fig. 1 and Fig. 2, according to the method of remanufacturing a scraper conveyor of Embodiment One, respectively measure the wear loss with a metal thickness detector, the standard and the process of repairing include: (1) Compare with a new product, when the wear loss of the middle plate 2 or 5 the base plate 3 is 5% of a new product, directly perform surfacing welding with the first wear block by using a wear welding wire or a wear welding rod; when the wear loss is 20% of a new product, firstly perform backing welding with an ordinary welding wire or an ordinary welding rod, and then perform surfacing welding with a first wear strip or a first wear block by using a wear welding wire or a wear welding 10 rod. During the underground work, limited to the spatial condition, the adopted process of surfacing welding includes: directly perform surfacing welding with the wear welding rod; or firstly perform backing welding with an ordinary welding rod and then perform surfacing welding with the wear strip and the wear block by using the wear welding rod; the welding process is shielded metal arc welding. 15 (2) When the wear loss of the middle plate 2 or the base plate 3 is 20% of a new product, wherein there are no more than three worn positions of which the wear loss is 40% of a new product, firstly perform backing welding with the ordinary welding wire or the ordinary welding rod, and then perform surfacing welding with the first wear strip or the first wear block by using the wear welding wire or the wear 20 welding rod. During the underground work, limited to the spatial condition, the adopted process of surfacing welding includes: directly perform surfacing welding with the wear welding rod; or firstly perform backing welding with the ordinary welding rod and then perform surfacing welding with the wear strip and the wear block by using the wear welding rod; the welding process is shielded metal arc 25 welding. (3) When the wear loss of the width of a monolateral chain track 12 of the channel ledge steel 1 is 15% of a new product, and the wear loss of the inside height of the chain track 13 is less than or equal to 6% of a new product, perform 11 surfacing welding with a second wear strip or a second wear block by using the wear welding wire or the wear welding rod. During the underground work, limited to the spatial condition, the adopted process of surfacing welding includes: directly perform surfacing welding with the wear welding rod; or firstly perform backing 5 welding with the ordinary welding rod and then perform surfacing welding with the wear strip and the wear block by using the wear welding rod; the welding process is shielded metal arc welding. When the wear loss of the width of the monolateral chain track 12 of the channel ledge steel 1 is 25% of a new product, and the wear loss of the inside 10 height of the chain track 13 is 9% of a new product, cover the entire inside wall of the chain track 13 of the channel ledge steel 1 with a plate. (4) When the wear loss of two side plates 41 of the headstock 4 is 5% of a new product, directly perform surfacing welding with the first wear strip by using the wear welding wire or the wear welding rod; when the wear loss of two side plates is 15 20% of a new product, firstly perform backing welding manually with the ordinary welding wire or the ordinary welding rod, and then perform surfacing welding with the first wear strip by using the wear welding wire or the wear welding rod. During the underground work, limited to the spatial condition, the adopted process of surfacing welding includes: directly perform surfacing welding with wear welding 20 rod; or firstly perform backing welding with the ordinary welding rod and then perform surfacing welding with the wear strip and the wear block by using wear welding rod; the welding process is shielded metal arc welding. The wear welding wire is Castolin wear welding wire; the welding process of Castolin wear welding wire is C02 shielded arc welding; the shielding gas is a 25 mixed gas of Ar and C02 with a mixture rate of 4:1; the gas flow is 17L/min; the diameter of the selected welding wire is <b 1.6mm; the metal transfer adopts spray transfer; the parameters of the current and the voltage are 290A and 30V respectively; the heat input is controlled under 14Kj/cm; the welding speed is 12 controlled at 290mm/min; the preheat temperature is 200-230 before welding. The ordinary welding wire is GHS-60 welding wire; the backing welding process of the ordinary welding wire is C02 shielded arc welding; the shielding gas is mixed gas of Ar and C02 with a mixture rate of 4:1; the gas flow is 17L/min; 5 the diameter of the selected welding wire is <b 1.6mm; the metal transfer adopts spray transfer; the parameters of the current and the voltage are 290A and 31V respectively; the heat input is controlled under 16Kj/cm; the welding speed is controlled at 210mm/min. The wear welding rod is Castolin welding rod; the welding process of Castolin 10 welding rod is shielded metal arc welding; wherein the welding current is 250A, and the welding speed is 150mm/min. The ordinary welding rod is E5015/E5016 welding rod; the welding process of ordinary welding rod is shielded metal arc welding; wherein the welding current is 120A, and the welding speed is 140mm/min. 15 Before performing the backing welding with the ordinary welding wire or the ordinary welding rod, preheat the parts to 80 -150 . Before performing the surfacing welding with the wear welding wire or the wear welding rod, preheat the parts to 200 -230 Embodiment Three: 20 As shown in Fig. 1 and Fig. 2, according to the method of remanufacturing a scraper conveyor of Embodiment One, respectively measure the wear loss with a metal thickness detector, the standard and the process of repairing include: (1) Compare with a new product, when the wear loss of the middle plate 2 or the base plate 3 is 8% of a new product, directly perform surfacing welding with a 25 first wear strip or a first wear block by using a wear welding wire or a wear welding rod; when the wear loss is 15% of a new product, firstly perform backing welding with an ordinary welding wire or an ordinary welding rod, and then perform surfacing 13 welding with a first wear strip or a first wear block by using a wear welding wire or a wear welding rod. During the underground work, limited to the spatial condition, the adopted process of surfacing welding includes: directly perform surfacing welding with a wear welding rod; or firstly perform backing welding with an 5 ordinary welding rod and then perform surfacing welding with the first wear strip and the first wear block by using the wear welding rod; the welding process is shielded metal arc welding. (2) when the wear loss of the middle plate 2 or the base plate 3 is 15% of a new product, wherein there are no more than three worn positions of which the wear loss 10 is 45% of a new product, firstly perform backing welding with the ordinary welding wire or the ordinary welding rod, and then perform surfacing welding with the first wear strip or the first wear block by using the wear welding wire or the wear welding rod. During the underground work, limited to the spatial condition, the adopted process of surfacing welding includes: directly perform surfacing welding with the 15 wear welding rod; or firstly perform backing welding with the ordinary welding rod and then perform surfacing welding with the first wear strip and the first wear block by using the wear welding rod; the welding process is shielded metal arc welding. (3) when the wear loss of the width of a monolateral chain track 12 of channel ledge steel 1 is 13% of a new product, and the wear loss of the inside height of the 20 chain track 13 is 8% of a new product, perform surfacing welding with a second wear strip or a second wear block by using the wear welding wire or the wear welding rod. During the underground work, limited to the spatial condition, the adopted process of surfacing welding includes: directly perform surfacing welding with the wear welding rod; or firstly perform backing welding with the ordinary 25 welding rod, and then perform surfacing welding with the second wear strip and the second wear block with the wear welding rod; the welding process is shielded metal arc welding. When the wear loss of the width of the monolateral chain track 12 of the 14 channel ledge steel 1 is 30% of a new product, and the wear loss of the inside height of the chain track 13 is 8.5% of a new product, cover the entire inside wall of the chain track 13 of the channel ledge steel 1 with a plate, wherein the thickness of the covering plate is half of the wear loss of the inside height of the chain track, and 5 the covering plate is a wear-resisting plate. (4) When the wear loss of two side plates 41 of headstock 4 is 7% of a new product, directly perform surfacing welding with the first wear strip by using the wear welding wire or the wear welding rod; when the wear loss of two side plates is 15% of a new product, firstly perform backing welding with the ordinary welding wire 10 or the ordinary welding rod, and then perform surfacing welding with the first wear strip by using the wear welding wire or the wear welding rod. During the underground work, limited to the spatial condition, the adopted process of surfacing welding includes: directly perform surfacing welding with the wear welding rod; or firstly perform backing welding with the ordinary welding rod and then perform 15 surfacing welding with the wear strip and the wear block by using the wear welding rod; the welding process is shielded metal arc welding. The wear welding wire is Castolin wear welding wire; the surfacing welding process of Castolin wear welding wire is C02 shielded arc welding; the shielding gas is a mixed gas of Ar and C02 with a mixture rate of 4:1; the gas flow is 20 17L/min; the diameter of the selected welding wire is 4 1.6mm; the metal transfer adopts spray transfer; the parameter of current and voltage is 320A and 31V respectively; the heat input is controlled as 20Kj/cm; the welding speed is controlled at 320mm/min; the preheat temperature is 230 before welding. The ordinary welding wire is GHS-60 welding wire; the backing welding 25 process of the ordinary welding wire is C02 shielded arc welding; the shielding gas is a mixed gas of Ar and C02 with a mixture rate of 4:1; the gas flow is 17L/min; the diameter of the selected welding wire is 4 1.6mm; the metal transfer adopts spray transfer; the parameters of the current and the voltage are 15 300A and 32V respectively; the heat input is controlled under 20Kj/cm; the welding speed is controlled at 220mm/min. The wear welding rod is Castolin welding rod; the welding process of Castolin welding rod is shielded metal arc welding; wherein the welding current is 260A, 5 and the welding speed is 160mm/min. The ordinary welding rod is E5015/E5016 welding rod; the welding process of ordinary welding rod is shielded metal arc welding; wherein the welding current is 140A, and the welding speed is 150mm/min. Before performing the backing welding with the ordinary welding wire or the 10 ordinary welding rod, preheat the parts to 80 -150 . Before performing the surfacing welding with the wear welding wire or the wear welding rod, preheat the parts to 200 -230 Embodiment Four: As shown in Fig. 1 and Fig. 2, according to the methods of remanufacturing a 15 scraper conveyor of Embodiments One to Three, the first wear strips locate at the planes of the middle plate 2 and the base plate 3. The first wear blocks locate at a connection end 21 of the middle plate and a connection end 31 of the base plate, which are just under the chains, the amount and interval distance of the first wear blocks match with the chains. The second wear strips locate in the inside of the 20 chain-track 13 of the channel ledge steel 1, and the second wear blocks locate at connection end 11 of the channel ledge steel 1. The first wear strip and second wear strip can form different textural patterns respectively. The pattern is set as one of a diamond shape, a fish-bone shape and a straight-bar-overlapped fish-scale shape or as a combination shape formed by 25 several shapes above. The first wear strips locate at the planes of the middle plate 2 and the base plate 3, the cladding width of the wear strip is 10-1 5mm, and the cladding thickness 16 is 1.5-3.5mm. The first wear blocks locate at the connection end 21 of the middle plate and a connection end 31 of the base plate, which are just under the chains, the amount and interval distance of the first wear blocks match with the chains, the specifications of first wear block is 60-100mm x 60-100mm. The second wear 5 strips locate inside the chain track 13 of channel ledge steel 1, the distances between the second wear strip and the two ends of the monolateral edge inside the chain track 13 are both 15-20mm, and the length of the second wear strip matches with the length of the channel ledge steel 1. The second wear blocks locate at a connection end 11 of the channel ledge steel 1, the length of the second wear block 10 is 80-100mm, the distances between the second wear block and the two ends of the monolateral edge inside the chain track 13 are both 15-20mm. During the cladding processes of the first wear strip and the second wear strip, the middle plate 2 or the base plate 3 and the channel ledge steel 1 should be preheated to 200-230 , intermittent cladding is adopted and the interval distance is 15 150-300mm, which can prevent the middle plate 2, the base plate 3 and the channel ledge steel 1 from deformation during the welding cladding. The preparation method of the wear strip and the wear block includes: single-pass weld is welded with the wear welding wire or the wear welding rod, and the overlap rate is 50%. The shielding gas is a mixed gas of Ar and C02 with a 20 mixture rate of 4:1; the gas flow is 15-20L/min; the diameter of the selected welding wire is <b 1.6mm; the metal transfer adopts spray transfer; the parameters of the current and the voltage is 270-325A and 27-31V respectively; the heat input is controlled under 20Kj/cm; the welding speed is controlled at 280-340mm/min; Before welding, preheat the parts to 200 -230 . 25 The wear welding rod is Castolin welding rod, wherein the welding current is 240-260A, and the welding speed is 140-160mm/min. During performing repair welding to the defective weld or performing surfacing welding to the worn positions with the ordinary welding wire or the ordinary welding 17 rod, the middle plate 2 or the base plate 3 and the channel ledge steel 1 should be heated to 80-150 , intermittent cladding is adopted and the interval distance is 150-300mm, which can prevent the middle plate 2, the base plate 3 and the channel ledge steel 1 form deformation during the surfacing welding. 5 The process of covering the entire inside wall of chain track 13 of the channel ledge steel 1 with a plate includes the following steps: Firstly, polish the inside wall of the chain track 13 of channel ledge steel 1 to expose its metallic luster. Get a wear-resisting plate which has the same shape with the inside wall of the 10 chain track 13 of the channel ledge steel 1, and drill a hole in the center of the wear-resisting plate, the diameter of the hole is 15-25mm, and the spacing is 100-300mm. Lay the wear-resisting plate on the inside wall of the channel ledge steel 1, the distances between the wear-resisting plate and the two end surfaces of the channel 15 ledge steel 1 are both 10-15mm, fix the steel plate on the inside of the chain track 13 of the channel ledge steel 1 through the center holes of the wear-resisting plate, and then perform surfacing welding between the periphery of the wear-resisting plate and the channel ledge steel 1 completely. Weld the wear-resisting plate to the Channel ledge steel 1 by C02 shielded arc 20 welding with the ordinary weld wire or the ordinary welding rod; the ordinary welding wire is GHS-60 welding wire, and the ordinary welding rod is E5015/E5016 welding rod. The process of performing backing surfacing with the ordinary welding wire is C02 shielded arc welding; the shielding gas is a mixed gas of Ar and C02 with a mixture rate of 4:1; the gas flow is 17L/min; the diameter of the 25 selected welding wire is <b 1.6mm; the metal transfer adopts spray transfer; the parameters of the current and the voltage are 280-300A and 30-32V respectively; the heat input is controlled under 20Kj/cm; the welding speed is controlled at 18 200-220mm/min; before welding, preheat the parts to 200 -230 , the welding current is 220-240A, and the welding speed is 120-150mm/min. E5015/E5016 welding rod is welded by the shielded metal arc welding, the welding current is 90-150A, and the welding speed is 120-150mm/min. 5 Experiment One: Get a new middle plate A and new channel ledge steel C, randomly select a middle plate Al clad with a wear strip and channel ledge steel C1 of which the inside is clad with the second wear strip, and respectively weigh them to obtain their pre-experiment weight. Make A, C, Al and C1 grind with 45-steel respectively, the 10 grinding time is set as 1.5 hours, and then weigh A, C, Al and C1 after grinding to obtain their post-experiment weight, thus obtain the experimental data as shown in Table one: Table one Material Pre-experiment Post-experiment Weight weight(g) weight(g) difference (g) New middle plate: A 7.5658 7.5672 0.0014 Clad middle plate: Al 8.0246 8.0230 0.0016 New channel ledge steel: C 12.2161 12.2146 0.0015 Clad channel ledge steel: 13.0834 13.0821 0.0013 C1 The above experiment is performed in a lab of Dazu Remanufacturing Co., 15 LTD., Shandong Energy Heavy Equipment Group. As shown in Table one, although there are weight differences between A and Al, C and C1, the weight difference between A and Al is very slight, and the weight difference between C and C1 is also very slight. Thus, in terms of wear resistance, the wear resistance of the clad part of this disclosure is equivalent to a new product. 20 Experiment Two: 19 Get a new chain track of a middle chute A of the scraper conveyor and a clad chain track of a middle chute B which is clad by the surfacing welding of this disclosure, randomly select six different positions of A, detect their hardness with a portable hardness tester and record the detected data. Randomly detect their 5 hardness of six different positions of B with the portable hardness tester, so as to obtain the experimental data shown in Table two: 10 Table two: Part 1 Part 2 Part 3 Part 4 Part 5 Part 6 (HRC) (HRC) (HRC) (HRC) (HRC) (HRC) A 56 55 57 54 55 53 B 58 54 54 56 56 58 The above experiment is performed in a lab of Dazu Remanufacturing Co., LTD., Shandong Energy Heavy Equipment Group. As shown in Table Two, the hardness of six detected positions shown in the table, there are three positions of the middle chute B which is clad by the surfacing 15 welding of this disclosure, the hardness of the three positions of the middle channel B is higher than the new plate A. Thus, in the aspect of the hardness performance, the hardness of the chain track of the middle chute B which is clad by surfacing welding of this disclosure is equivalent to the hardness of the new chain track of the middle chute A of the scraper conveyor, even better than the performance of the 20 new product A. Additionally, it should be understood that even though this specification is described as exemplary embodiments, each embodiment include not only one method solution, which is considered to make this specification clear. The 20 specification should be deem as a whole by those ordinary skilled in this art, the method solution of every embodiment can be can be properly devised to form other embodiments understood by those skilled in this art. 21