Large composite roller centrifugal casting cold mold inner hole additive repairing system and method

Abstract

The invention discloses a large composite roller centrifugal casting cold mold inner hole additive repairing system and method, and belongs to the technical field of metal material repairing and remanufacturing. Comprising an inclined roller carrier used for placing a cold mold, a cross manipulator used for conveying welding flux, an automatic feeding device used for feeding the welding flux, a vibrating screen used for screening welding slag and residual welding flux, and a variable-power heat preservation furnace used for heat preservation of the cold mold. The method comprises the following steps: processing and detecting before welding; preheating before welding; surfacing welding is conducted through a large composite roller centrifugal casting cold mold inner hole additive repairing system; performing post-weld heat treatment; and processing after welding. According to the method, high-efficiency, automatic and continuous additive remanufacturing can be achieved, large-thickness and large-area rapid repairing is met, the temperature between the layers is accurately controlled, and high-strength metallurgical bonding between the base body layer and the cladding layer is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal material repair and remanufacturing, and particularly relates to a large composite roller centrifugal casting cold-type inner hole additive repair system and method. BACKGROUND

[0002] As the core consumable of modern metallurgical rolling mill, the performance of the composite roller directly determines the surface quality, production efficiency and comprehensive cost of the equipment. The traditional whole roller is gradually replaced by the composite roller because it is difficult to balance the surface hardness and the toughness of the core. The composite roller adopts a heterogeneous structure of "hard outside and tough inside", the outer layer is usually high-chromium cast iron, high-speed steel and other high-wear-resistant materials, and the inner layer is nodular cast iron or low-alloy cast steel, and metallurgical bonding is achieved through centrifugal casting. However, the manufacturing of the composite roller is highly dependent on the precision and stability of the cold-type mold - the size deviation of the cold-type inner hole will cause uneven thickness of the outer layer of the roller, and will cause stress concentration and even peeling accidents in the rolling process.

[0003] During the centrifugal casting process, the cold-type needs to withstand the severe thermal shock of the high-temperature metal liquid at 1400-1600 DEG C under high-speed rotation (200-800 rpm). The metal liquid adheres to the inner wall of the cold-type to form the outer layer of the roller under the action of centrifugal force, and the cold-type inner surface has a large instantaneous heat flux density at this stage, which produces a periodic thermal stress as high as 300-500 MPa. In addition, the cold-type material will gradually deteriorate due to the following mechanisms under the long-term high-temperature, high-pressure and thermal cycle load: 1. Mechanical wear: the friction caused by the solidification shrinkage of the metal liquid causes the inner hole diameter to gradually expand, and local damage will occur in the inner hole during the pulling separation process of the cold-type and the roller after forming; 2. Thermal fatigue cracks: rapid cooling and heating cycles cause network cracks; 3. Oxidation peeling: the high-temperature oxidation layer falls off due to the difference in thermal expansion coefficient with the matrix, which aggravates the surface roughness.

[0004] At present, there are mainly two ways after the size of the centrifugal casting cold-type is out of tolerance. The first way is to replace the whole cold-type, but the manufacturing cost is high, and the delivery cycle is long, which seriously affects the production continuity. The second way is additive repair, and the welding arc welding and laser cladding technology can locally repair, but the accessibility is poor, the traditional fixed type cladding head is difficult to enter the cold-type inner hole, and cannot adapt to the curved trajectory, and the forming efficiency is low, and the single pass can only cladding height 1~2mm, which cannot meet the efficient repair of the large wall thickness cold-type.

[0005] As the core component of centrifugal casting roller, the cold type is subjected to high temperature, high pressure and thermal cycle load for a long time, which is easy to cause inner hole wear, crack and other failures. The traditional repair method such as mechanical reaming + inner bushing hot installation (such as patent CN103350313B) has problems such as complex process, high cost, insufficient size precision after repair and the like. Although the existing submerged arc welding technology can be used for repair, the following challenges are faced: 1. Difficult to clean the welding slag: the overall length of the cold type is relatively long (2-5 meters), and the welding slag needs to be cleaned manually, which is low in efficiency and high in labor intensity; 2. Inconvenient to add flux: the traditional short-distance inner wall welding method using manual addition of flux in the hopper or pre-paved flux on the inner wall is not suitable for the long inner hole of the cold type; 3. Difficult to control the temperature between layers: the welding thickness is relatively thick (>10mm), the welding weight is relatively large (for example, 20mm single-side welding, the welding amount is nearly 1t), and the welding time is relatively long, so that cracks are easy to occur due to temperature fluctuation during the welding process; 4. Many joint defects: the welding wire joint is easy to produce start-stop arc defects, and due to improper heat input control, it is easy to produce pores, slag inclusion and un-melted defects, which affect the repair quality.

[0006] Therefore, there is an urgent need for a cold type repair method integrating automatic equipment, high-precision temperature control and special materials. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a large composite roller centrifugal casting cold type inner hole additive repair system and method, which can realize high efficiency, automation and continuous additive remanufacturing, meet the requirements of rapid repair of large thickness and large area, accurately control the temperature between layers, and realize high-strength metallurgical bonding between the base layer and the cladding layer.

[0008] To solve the above technical problems, the technical scheme adopted by the present application is: A large composite roller centrifugal casting cold type inner hole additive repair system, comprising an inclination roller frame for placing the cold type, a cross operating machine for flux conveying, an automatic feeding device for flux feeding, a vibrating screen for screening welding slag and residual flux, and a variable power holding furnace for holding the cold type; The inclination roller frame comprises an inclined frame body and rollers arranged on both sides of the frame body. Cross operation machine, including vertical beam, horizontal beam, micro-feeding auger arranged on the pipe wall of horizontal beam, welding head module arranged on the welding end of horizontal beam, beam up-down moving motor arranged on the top end of vertical beam, beam horizontal moving motor arranged at the intersection of vertical beam and horizontal beam, feeding port arranged on the pipe wall of horizontal beam far from welding end and discharging port arranged on the lower pipe wall of welding end of horizontal beam, the discharging port is connected with welding head module, the beam up-down moving motor controls horizontal beam to move up and down along vertical beam, the beam horizontal moving motor controls horizontal beam to move horizontally, changes the position of welding head module, The automatic feeding device comprises a flux upper bin, a pneumatic conveying device, a flux lower bin and a conveying pipe. The vibrating screen is arranged below the inclined end of the slope roller frame. The variable-power holding furnace comprises a first holding area arranged at a middle position and a second holding area arranged at both sides.

[0009] The further improvement of the technical scheme of the present application is that the angle range of the inclination of the frame body is 1°-3°, and the rollers on both sides are in the form of a conical surface.

[0010] The further improvement of the technical scheme of the present application is that the automatic feeding device transports the flux in the flux lower bin to the flux upper bin at the upper end of the feeding port of the cross operation machine through positive pressure or negative pressure of air, the flux is forwarded through the rotating screw of the auger, and the flux is transported to the discharge tee joint of the welding head module through the discharging port.

[0011] The further improvement of the technical scheme of the present application is that the welding head module is provided with a plurality of head parts.

[0012] The further improvement of the technical scheme of the present application is that the power of the first holding area is twice that of the second holding area.

[0013] A large composite roller centrifugal casting cold-type inner hole additive repair method, comprising the following steps: S1, pre-welding processing and detection; S2, pre-welding preheating; S3, applying a large composite roller centrifugal casting cold-type inner hole additive repair system to carry out surfacing welding; S4, post-welding heat treatment; S5, post-welding processing: the repaired cold-type inner hole is processed as a whole, turned according to the finished product size, and then subjected to nondestructive testing.

[0014] Further improvement of the technical scheme of the present application is that in S1, the cold-type inner hole needing repair is processed as a whole, single-side turning is performed according to the finished product size, and then non-destructive testing is performed, including ultrasonic flaw detection and coloring flaw detection, and the position with defects is processed until no defects are left.

[0015] Further improvement of the technical scheme of the present application is that in S2, the cold-type is preheated in a whole-furnace manner, the preheating temperature is 350-400 DEG C, and the temperature is kept for 4-8 h.

[0016] Further improvement of the technical scheme of the present application is that S3 specifically comprises the following steps: S31 places the cold-type on the inclined roller frame, uses a mechanical anti-channeling clamp on the end surface of the lower side of the roller to prevent the cold-type from falling due to serious channeling; S32 adjusts the up-down motor of the cross-operating machine and the horizontal moving motor of the cross beam, so that the welding head module starts from the lower side of the cold-type, facilitates the observation and adjustment of the starting arc, and the welding slag and residual flux automatically gather to the lower side when the welding head module spirally moves to the higher side of the cold-type; S33 realizes the automatic separation of the flux and the welding slag after the welding slag and residual flux are screened by the outlet position vibrating screen, the welding slag and fine powder are stored in a ton bag and are lifted away, the recovered 8-40 mesh flux is stored in the lower flux bin, the flux is conveyed to the feeding port above the horizontal cross beam of the cross-operating machine by the automatic feeding device, and the flux is sent to the lower three-way joint of the welding head module by the feeding auger, so that the recycling of the flux is realized; S34 welding parameters: chemical composition of the welding wire: C≤0.05%, Si≤0.3%, Mn 1-3%, Cr 1.5-2.5%, Mo 1-2%, Ni 2-4%, Co 0.5-1.5%, S≤0.01%, P≤0.01%, the balance of Fe, and additionally adding trace rare earth element La with a content of 0.01%-0.05% as a grain refiner; diameter of the welding wire is φ3.2, current is 300-500 A, voltage is 30-40 V, welding speed is 30-60 cm / min, and for the single-side thickness of 20 mm, the total cycle is 10-15 days; Final mechanical properties of the welding wire: tensile strength≥600 MPa, yield strength≥400 MPa, elongation≥15%, and ferrite content≤40%; the post-welding surface is free of defects with a diameter≥φ2 mm, and the thermal fatigue cycle is≥250 times without cracks; S35 uses a cold-type welding dedicated variable-power holding furnace to ensure that the interlayer temperature is uniform, and the temperature difference is≤20 DEG C, and the whole cold-type interlayer temperature is above 300 DEG C; S36 cancel the original 50 kg welding wire disc, make special welding wire disc, single disc weight is 300-500 kg, single disc welding wire length meets the single-layer jointless welding demand; if sudden failure stops, special length polishing tool is used to process start-stop arc area.

[0017] Further improvement of the technical scheme of the application is that in S4, after welding, the cold type is integrally loaded into a furnace and heated to 550-650 DEG C, and kept for 4-8 hours, and slowly cooled to room temperature, and the hardness is controlled to 30-40 HSD.

[0018] Due to the adoption of the above technical scheme, the application has the following technical progress: 1. On the equipment, the application realizes automatic collection and cleaning of welding slag by using the slope roller frame + vibrating screen, the efficiency is improved by 10%, and the labor intensity is reduced by 20%.

[0019] 2. On the equipment, the application solves the problem of long cold type welding agent addition by using pneumatic conveying + feeding auger system, and the labor intensity is reduced by 10%.

[0020] 3. In the process, the application adopts a special holding furnace + large disc welding wire to ensure interlayer temperature stability and jointless welding, and the defect rate is reduced to ≤0.5%.

[0021] 4. In the material, the application uses ultra-low carbon (C≤0.05%) + low sulfur and phosphorus (S / P≤0.01%) welding wire to significantly improve the crack resistance.

[0022] 5. In the material, the application adds rare earth elements to the Cr-Mo-Ni-Co alloy system to endow the welding layer with high temperature resistance (≤800 DEG C) and thermal fatigue resistance, and the service life is ≥300 times.

[0023] 6. In the application, one or more machine heads are arranged on the welding head module, and with the increase of the number of machine heads, the deposition efficiency is equivalent to increase.

[0024] 7. In the application, a cross operation machine can be arranged on both sides of the cold type, and the two sides can be overlaid at the same time, thereby improving the efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a large composite roller centrifugal casting cold type inner hole additive repair system schematic diagram in the application; Figure 2 It is a special welding wire metallographic structure under 100 µm in the application; Figure 3 It is a special welding wire metallographic structure under 20 µm in the application; Wherein, 1, cold type; 2, slope roller frame; 3, cross operation machine, 31, feeding auger, 32, welding head module, 33, horizontal beam, 34, horizontal beam horizontal movement motor, 35, horizontal beam vertical movement motor; 4, automatic feeding device, 41, upper flux bin, 42, pneumatic conveying device, 43, lower flux bin, 44, flux conveying pipe, 45, flux conveying auger; 5, vibrating screen. DETAILED DESCRIPTION

[0026] The application will be further described below in conjunction with the drawings and embodiments: In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0027] In addition, in the description of the present application, "several" means at least two, for example, two, three, etc., unless otherwise explicitly and specifically limited.

[0028] As Figure 1 shown, a large composite roller centrifugal casting cold type 1 inner hole additive repair system, including for placing the cold type 1 slope roller frame 2, for the cross operation machine 3 of flux conveying, for the automatic feeding device 4 of flux feeding, for the vibrating screen 5 of slag and residual flux screening and for the variable power holding furnace of cold type 1 holding; The slope roller frame 2 comprises an inclined frame body and rollers arranged on both sides of the frame body: the inclination angle of the frame body ranges from 1° to 3°; The roller frame for surfacing is different from the ordinary roller frame, the rollers on both sides of which are in the form of conical surfaces and are distributed with a height difference, and the inclination angle ranges from 1° to 3°; during surfacing, the slag and residual flux can be automatically gathered and flowed to the lower side and directly collected in the vibrating screen 5 placed below the cold type 1; at the same time, to prevent the cold type 1 from deviating to the lower side of the roller during rotation, a mechanical anti-channeling device is installed at the lower side, which can ensure that the cold type 1 does not move by a larger resistance; The cross operation machine 3 includes a vertical beam, a horizontal beam 33, a micro feeding auger 31 arranged on the pipe wall of the horizontal beam 33, a welding head module 32 arranged on the welding end of the horizontal beam 33, a horizontal beam up-down moving motor 35 arranged on the top end of the vertical beam, a horizontal beam horizontal moving motor 34 arranged at the intersection of the vertical beam and the horizontal beam 33, a feeding port arranged on the pipe wall of the horizontal beam 33 away from the welding end, and a discharging port arranged on the lower pipe wall of the welding end of the horizontal beam 33; the discharging port is connected with the welding head module 31; one or more welding heads are arranged on the welding head module 32; the horizontal beam up-down moving motor 35 controls the up-down movement of the horizontal beam 33 along the vertical beam, and the horizontal beam horizontal moving motor 34 controls the horizontal movement of the horizontal beam 33, so as to change the position of the welding head module 31. The automatic feeding device 4 includes a flux upper bin 41, a pneumatic conveying device 42, a flux lower bin 43, and a conveying pipe; the conveying pipe includes a flux conveying pipe 44 arranged between the flux upper bin 41 and the pneumatic conveying device 42, and a flux conveying auger 45 arranged between the pneumatic conveying device 42 and the flux lower bin 43. The automatic feeding device 4 conveys the flux in the flux lower bin 43 to the flux upper bin 41 on the upper end of the feeding port of the cross operation machine 3 in the form of pneumatic positive pressure or negative pressure; the flux is forwarded by the rotating screw of the auger, and is conveyed to the discharging tee joint of the welding head module 31 through the discharging port; when the flux bin is insufficient, new flux can be supplemented by the crown block or other equipment.

[0029] The linear vibrating screen 5 is arranged below the inclined end of the slope roller frame 2. The linear vibrating screen 5 has a specification of 2000mm in length and 500mm in width, and the mesh number of the screen is 8-40 meshes; the oversize and undersize are recycled by ton bags respectively, and the 8-40 mesh particles after screening are stored in the flux bin for use.

[0030] The variable-power heat preservation furnace includes a first heat preservation zone arranged at the middle position and a second heat preservation zone arranged at both sides; the power of the first heat preservation zone is twice that of the second heat preservation zone. In view of the problems of the long length of the cold type 1, the fast heat dissipation of the two end surfaces, the low heat input of a single welding head, and the long surfacing period, a heat preservation furnace special for the welding of the cold type 1 is made; the two zones are independently controlled in temperature; the middle part is the first heat preservation zone; the two side parts are the second heat preservation zone; the interlayer temperature is uniformly ensured (the temperature difference is less than or equal to 20℃); and the interlayer temperature of the whole cold type 1 is above 300℃.

[0031] The large composite roller centrifugal casting cold type inner hole additive repair system realizes the automatic, continuous and uniform addition of the flux in the surfacing process, and ensures the recycling of the flux.

[0032] A large composite roller centrifugal casting cold type 1 inner hole additive repair method, comprising the following steps: S1, welding processing and detection: The cold type 1 inner hole to be repaired is processed as a whole, and is turned (>10mm) according to the finished product size. Then, nondestructive testing (ultrasonic flaw detection + color flaw detection) is carried out. The position with defects is processed until there is no defect; S2, preheating before welding; The cold type 1 is preheated in a whole furnace, and the preheating temperature is 350-400℃, and the holding time is 4-8h; S3, applying a large composite roller centrifugal casting cold type 1 inner hole additive repair system for surfacing; S31 places the cold type 1 on the inclined roller frame 2, and uses a mechanical anti-channeling clamp on the end surface of the lower side of the cold type 1 roller to prevent the cold type 1 from falling due to serious channeling; S32 adjusts the up-down moving motor 35 and the horizontal moving motor 34 of the cross operating machine 3 to make the welding head module 32 start from the lower side of the cold type 1, which is convenient for observing and adjusting the arc starting bead, and when the welding head module 32 moves spirally to the higher side of the cold type 1, the welding slag and residual flux automatically gather on the lower side, which will not affect the welding bead; S33, after the welding slag and residual flux are screened by the outlet position vibrating screen 5, the flux and the welding slag are automatically separated, the welding slag and fine powder are stored in a ton bag and are lifted away, the recovered 8-40 mesh flux is stored in a flux bin, the flux is conveyed to the feeding port above the horizontal beam 33 of the cross operating machine 3 through a dynamic feeding device, and then the flux is sent to the discharge tee joint of the welding head module through the feeding auger 31, so that the recycling of the flux is realized; S34, welding parameters: the welding wire adopts an ultra-low carbon welding wire composition design, the chemical composition (wt%) is C≤0.05%, Si≤0.3%, Mn 1-3%, Cr 1.5-2.5%, Mo 1-2%, Ni 2-4%, Co 0.5-1.5%, S≤0.01%, P≤0.01%, the balance is Fe, and trace rare earth element La (content 0.01%-0.05%) is additionally added as a grain refiner to inhibit the formation of coarse carbides in the welding process, optimize the stability of the welding wire droplet transfer, and reduce spatter; the welding wire diameter is φ3.2, the current is 300-500A, the voltage is 30-40V, the welding speed is 30-60cm / min, and for example, the total cycle is 10-15 days for a single side thickness of 20mm; The final mechanical properties of the welding wire are as follows: tensile strength≥600MPa, yield strength≥400MPa, elongation≥15%, and ferrite content≤40%; there is no defect with a diameter≥φ2mm on the surface after welding, and the thermal fatigue cycle is≥250 times without cracks; S35 uses a variable-power holding furnace dedicated to cold-type 1 welding to realize accurate control of interlayer temperature and ensure uniform interlayer temperature (temperature difference ≤20℃), and the interlayer temperature of the entire cold-type 1 is above 300℃; S36 is to cancel the original 50 kg welding wire reel (for example, 20 mm single-sided cladding requires welding 9-11 layers, the cladding amount is 90-110 kg, the welding wire reel needs to be replaced frequently, and each layer needs to be stopped for 2-3 times due to replacement of the welding wire, the start-stop arc position may affect the welding quality, and since the cold-type 1 is long, the position of the re-ignition is also not easy to accurately position), a special welding wire reel is made, the single reel weight is 300-500 kg, the single reel welding wire length meets the single-layer jointless welding requirement, and the number of joints is greatly reduced; if the machine is stopped due to sudden failure, a special lengthening grinding tool is used to process the start-stop arc area.

[0033] S4, post-weld heat treatment; Post-heat treatment: after welding, the entire cold-type 1 is heated to 550-650℃ in a furnace, and then is kept for 4-8h and slowly cooled to room temperature, and the hardness is controlled to 30-40HSD.

[0034] S5, post-weld processing; The repaired inner hole of the cold-type 1 is processed as a whole, is turned according to the finished product size, and then is subjected to nondestructive testing (ultrasonic flaw detection + color flaw detection). Embodiment

[0035] Taking the repair of a certain cold-type 1 as an example Cold-type 1 parameters: length 2350 mm, inner hole diameter 788 mm, repair thickness 20 mm; Welding wire composition: C 0.04%, Si 0.25%, Mn 1.8%, Cr 1.7%, Mo 1.2%, Ni 3.0%, Co 0.9%, La 0.03%; Process parameters: current 450 A, voltage 35 V, welding speed 45 cm / min, interlayer temperature control 320±10℃; Detection results: hardness 35HSD, tensile strength 620 MPa, no cracks after 300 times of thermal fatigue cycles, and no defects in ultrasonic detection.

[0036] In summary, the present application can realize high efficiency, automation and continuous additive remanufacturing, meet the requirements of rapid repair of large thickness and large area, accurately control the interlayer temperature, and realize high-strength metallurgical bonding between the base layer and the cladding layer.

Claims

1. A large composite roller centrifugal casting cold mold inner hole additive repair system, characterized by: It includes an inclined roller frame (2) for placing the cold mold (1), a cross operating machine (3) for conveying flux, an automatic feeding device (4) for adding flux, a vibrating screen (5) for screening welding slag and residual flux, and a variable power holding furnace for holding the cold mold (1); The inclined roller frame (2) comprises a frame body arranged obliquely and rollers arranged on both sides of the frame body; A cross manipulator (3) comprises a vertical beam, a horizontal beam (33), a micro-feeding auger (31) arranged on the pipe wall of the horizontal beam (33), a welding head module (32) arranged at the welding end of the horizontal beam (33), a beam vertical movement motor (35) arranged at the top of the vertical beam, a beam horizontal movement motor (34) arranged at the intersection of the vertical beam and the horizontal beam (33), a feed port arranged on the upper pipe wall of the horizontal beam (33) away from the welding end, and a discharge port arranged on the lower pipe wall of the welding end of the horizontal beam (33); the discharge port is connected to the welding head module (31); the beam vertical movement motor (35) controls the horizontal beam (33) to move up and down along the vertical beam, and the beam horizontal movement motor (34) controls the horizontal beam (33) to move horizontally, thereby changing the position of the welding head module (31); The automatic feeding device (4) includes an upper flux silo (41), a pneumatic transmission device (42), a lower flux silo (43), and a transmission pipe; the transmission pipe includes a flux delivery pipe (44) arranged between the upper flux silo (41) and the pneumatic transmission device (42), and a flux transmission auger (45) arranged between the pneumatic transmission device (42) and the lower flux silo (43); The vibrating screen (5) is arranged below the inclined end of the inclined roller frame (2); The variable power holding furnace comprises a first holding zone arranged in the middle and second holding zones arranged on both sides.

2. The large composite roller centrifugal casting cold mold inner hole additive repair system according to claim 1 is characterized by: The frame has an inclination angle ranging from 1° to 3°; and the rollers on both sides are in the form of cone surfaces.

3. The large composite roller centrifugal casting cold mold inner hole additive repair system according to claim 1 is characterized by: The automatic feeding device (4) conveys the flux in the lower flux hopper (43) to the upper flux hopper (41) at the upper end of the feed port of the cross manipulator (3) through pneumatic positive pressure or negative pressure. The flux is fed forward by the rotating spiral of the auger and conveyed to the unloading tee of the welding machine head module (31) through the discharge port.

4. The large composite roller centrifugal casting cold mold inner hole additive repair system according to claim 1 is characterized by: The welding head module (32) is provided with a plurality of heads.

5. The large composite roller centrifugal casting cold mold inner hole additive repair system according to claim 1 is characterized by: The power of the first heat preservation zone is twice that of the second heat preservation zone.

6. A method for repairing the inner hole of a centrifugal casting cold mold of a large composite roller by additive manufacturing, characterized by: The application of the large composite roller centrifugal casting cold mold inner hole additive repair system according to any one of claims 1 to 5 comprises the following steps: S1. Pre-welding processing and inspection; S2, preheating before welding; S3, using a large composite roller centrifugal casting cold mold inner hole additive repair system for surfacing; S4, post-weld heat treatment; S5. Post-weld processing: The inner hole of the repaired cold mold (1) is processed as a whole, turned according to the finished product size, and then non-destructive testing is performed.

7. The large composite roller centrifugal casting cold mold inner hole additive repair system according to claim 6, characterized in that: In S1, the inner hole of the cold type (1) that needs to be repaired is processed as a whole, and is turned by single-side turning according to the finished product size. After that, non-destructive testing is performed, including ultrasonic testing and color flaw detection, and the defective positions are processed until there are no more defects.

8. The large composite roller centrifugal casting cold mold inner hole additive repair system according to claim 6, characterized in that: In S2, the cold type (1) is preheated by the overall furnace loading method, the preheating temperature is 350-400℃, and the heat preservation time is 4-8h.

9. The large composite roller centrifugal casting cold mold inner hole additive repair system according to claim 6, characterized in that: S3 specifically includes the following steps: S31 Place the cold mold (1) on the inclined roller frame (2), and use a mechanical anti-collision top tightener on the lower side of the roller to prevent the cold mold (1) from falling after serious movement; S32 adjusts the beam up-down moving motor (35) and the beam horizontal moving motor (34) on the cross manipulator (3) so that the welding head module (32) starts the arc from the lower side of the cold profile (1), which facilitates observation and adjustment of the arc starting weld bead, and when the welding head module (32) moves spirally toward the higher side of the cold profile (1), the welding slag and residual flux that fall off during surfacing welding automatically gather toward the lower side; S33 welding slag and residual flux are sieved by the vibrating screen (5) at the outlet position to realize automatic separation of flux and welding slag, welding slag and fine powder are stored in ton bags and hoisted away, and the recovered 8-40 mesh flux is stored in the lower flux hopper (43), and the flux is transported to the feed port above the horizontal beam of the cross manipulator (3) through the automatic feeding device (4), and then sent to the unloading tee of the welding head module (32) through the feeding auger (31), thereby realizing the recycling of flux; S34 welding parameters: Wire chemical composition (wt%): C ≤ 0.05%, Si ≤ 0.3%, Mn 1-3%, Cr 1.5-2.5%, Mo 1-2%, Ni 2-4%, Co 0.5-1.5%, S ≤ 0.01%, P ≤ 0.01%, balance Fe. In addition, a trace amount of rare earth element La is added, with a content of 0.01%-0.05% as a grain refiner; wire diameter φ3.2, current 300-500A, voltage 30-40V, welding speed 30-60cm / min. Taking a single-side thickness of 20mm as an example, the total cycle time is 10-15 days. Final welding wire mechanical properties: tensile strength ≥600MPa, yield strength ≥400MPa, elongation ≥15%, ferrite content ≤40%; no surface defects with a diameter of ≥φ2mm after welding, no cracks after thermal fatigue cycles ≥250 times; S35 uses a variable power holding furnace dedicated to cold type (1) welding to ensure uniform temperature between layers with a temperature difference of ≤20°C. The temperature between the entire cold type (1) layer is above 300°C. S36 has replaced the original 50kg welding wire reel with a dedicated one. The weight of a single reel is between 300-500kg, and the length of the welding wire on a single reel meets the requirements of single-layer jointless welding. If the machine stops due to a sudden fault, a dedicated extended grinding tool is used to process the start and stop arc areas.

10. The large composite roller centrifugal casting cold mold inner hole additive repair system according to claim 6, characterized in that: In S4, after welding, the cold mold (1) is heated to 550-650℃ in a furnace, kept warm for 4-8 hours, and slowly cooled to room temperature. The hardness is controlled to 30-40HSD.

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