Welding structure and process for removing broken screw rod on ball mill manhole body

Abstract

The application discloses a kind of welding structure and process for removing broken screw on manhole body of ball mill, and ball mill includes ball mill barrel, manhole is opened on ball mill barrel, and a plurality of threaded holes are opened on the edge of manhole, thread tooth is arranged on the inside of threaded hole, and a plurality of broken screws with top lower than the orifice of threaded hole are threadedly connected to the inside of threaded hole;The welding structure includes T-shaped inner sleeve, screw extension welding part and matched nut;T-shaped inner sleeve is arranged in threaded hole, its bottom is in contact with the top of broken screw, and the top is provided with the matched nut;Screw extension welding part is arranged in the inner hole of T-shaped inner sleeve and matched nut, it is welded by welding wire, and its bottom and outer side are respectively welded and fixed with the top of broken screw rod and the inside of T-shaped inner sleeve and matched nut.Application of the present application can quickly implement the removal of broken screw on manhole body of ball mill, save equipment running time, reduce procurement cost, reduce long-term shutdown loss, and provide protection for reasonable production of ball mill.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a welding structure and process for removing a broken screw from the manhole body of a ball mill. Background Technology

[0002] Ball mills are key equipment for further pulverizing materials after they have been crushed, and are also core equipment in mineral processing enterprises. For example, the MQY4675 ball mill has a cylinder made of Q345 stainless steel and weighs approximately 300 tons. The main components of this type of ball mill include: journals, end covers, and the cylinder body. Figure 1 As shown, the ball mill body includes a ball mill cylinder 3. Manholes are symmetrically designed on the ball mill cylinder 3, allowing workers to enter and exit the cylinder and observe its operation over the long term. Threaded holes 9 are symmetrically arranged on the cylinder along the edge of the manholes. To prevent water and material leakage during production, manhole covers 7 are typically fixedly connected to the cylinder body 3 via locking screws 8 and threaded holes 9. Because a wear-resistant layer is installed on the inner wall of the cylinder 3, the locking screws 8 are usually not connected through the cylinder, but rather installed on the cylinder 3. Due to centrifugal force and friction, the grinding media and ore inside the cylinder are lifted to a certain height by the cylinder liner and then detach from the cylinder wall, falling freely or being thrown down, causing the ore to be crushed by impact and abrasion. Long-term full-load operation directly leads to broken screws 4 in parts of the locking screws 8. Some broken screws are higher than the cylinder body and can be removed and replaced with new screws using mechanical tools; others are inside the cylinder body (e.g., Figure 4 As shown, the broken screw cannot be directly removed using mechanical tools. If the broken screw is not removed and replaced with a new locking screw in time, water and material leakage will occur at the opening of the cylinder covered by the manhole cover, seriously affecting the production rhythm. If conventional methods such as cutting, wrenching, knocking, hammering, and drilling are used to remove the broken screw inside the cylinder wall, it will be impossible to remove it without damaging the cylinder body, which will pose a safety hazard to the normal production of the ball mill. Summary of the Invention

[0003] To address the problem of difficulty in removing broken screws from the threaded holes of ball mill manholes in the prior art, this invention provides a welding structure and process for removing broken screws from the ball mill manhole body. This process enables rapid removal of broken screws from the ball mill manhole body, saving equipment operating time, reducing procurement costs, minimizing losses from prolonged downtime, and ensuring efficient ball mill production.

[0004] The technical solution of this invention to solve the technical problem is as follows:

[0005] This invention discloses a welded structure for removing a broken screw from a manhole body of a ball mill. The ball mill includes a ball mill cylinder with a manhole and multiple threaded holes along its edge. Threads are provided inside the threaded holes, and several broken screws, with their tops lower than the openings of the threaded holes, are threadedly connected to the inside of these holes. The welded structure includes a T-shaped inner sleeve, a screw extension welded component, and a matching nut. The T-shaped inner sleeve is disposed within the threaded holes, its bottom contacting the top of the broken screw, and the matching nut is disposed at its top. The screw extension welded component is disposed within the inner holes of the T-shaped inner sleeve and the matching nut, and is welded by welding wire. Its bottom and outer side are welded and fixed to the top of the broken screw and the inner sides of the T-shaped inner sleeve and the matching nut, respectively.

[0006] Furthermore, the T-shaped inner sleeve is machined from a steel pipe, with an outer diameter smaller than the diameter of the broken screw and a wall thickness of 1.5–2 mm.

[0007] Furthermore, the matching nut is machined from round steel.

[0008] Furthermore, the inner diameter of the T-shaped inner sleeve is the same as that of the matching nut.

[0009] This invention discloses a welding process for removing a broken screw from a ball mill manhole. The ball mill includes a ball mill cylinder with a manhole and multiple threaded holes along its edge for installing a manhole cover via locking screws. The threaded holes have threads on their inner sides and are connected to the locking screws. Several locking screws break, forming broken screws with their tops lower than the openings of the threaded holes. The process involves: cleaning the top of the broken screw to expose its metallic luster; restoring the threads of the threaded holes above the broken screw; installing a T-shaped inner sleeve in the threaded hole; welding a screw extension weldment, fusing its outer side and bottom to the T-shaped inner sleeve and the top of the broken screw, respectively; placing a matching nut on the top surface of the T-shaped inner sleeve; continuing to weld the screw extension weldment, ensuring its outer side is firmly welded to the matching nut; tightening the matching nut with a conventional adjustable wrench without damaging the main body; and then rotating the screw extension weldment counterclockwise, removing it along with the T-shaped inner sleeve and the broken screw from the threaded hole.

[0010] Furthermore, the specific method for removing the broken screw is as follows:

[0011] Step 1: Preparation before welding

[0012] 1.1) Welding equipment: Digitally controlled inverter manual DC TIG welding machine, using ER50-6 welding wire;

[0013] 1.2) Welding position: Flat welding;

[0014] 1.3) Pre-welding requirements: The welding area must be free of oil, oxide layer and moisture, and must show a metallic luster;

[0015] 1.4) Welding technical requirements: The weld overlay layer must be fused to protect the inner thread of the threaded sleeve and the bottom layer;

[0016] 1.5) Welding material: Grade 8.8 high-strength screw;

[0017] 1.6) Auxiliary facilities: templates, magnifying glasses, face masks, gloves, slag removal hammers, hammers, chisels, files, wire brushes, sandpaper, steel rulers, spirit levels, adjustable wrenches, straight grinders, angle grinders, wire cutters, hacksaw blades, personal protective equipment;

[0018] 1.7) Welding process parameters: Welding parameters are determined based on the welding equipment, welding materials, workpiece material, and welding requirements;

[0019] Step Two: Implementation:

[0020] 2.1) Rotate the ball mill cylinder to a horizontal position to remove moisture, oil, and other contaminants from the broken screw location using an oxy-acetylene flame. Then, grind away rust using sandpaper or a grinding wheel. Next, clean the top of the broken screw using an angle grinder. Once the upper surface of the broken screw is smooth and shiny, restore the threads on the upper part of the threaded hole using manual mechanical tools. Then, install a T-shaped inner sleeve that fits the threaded hole, ensuring that the bottom of the T-shaped inner sleeve is in contact with the top of the broken screw. Finally, weld the screw extension weldment using a digitally controlled inverter manual DC argon arc welding machine.

[0021] 2.2) When performing the root pass welding, start from the junction of the T-shaped inner sleeve and the top of the broken screw. The welding sequence should be circular, proceeding from the outside in. After the arc is ignited, preheat the workpiece for 3-5 seconds at the starting point to form a molten pool before feeding the wire. Use a small crescent-shaped welding method. Because the welding wire and torch are welding inside the threaded hole, the horizontal angle between the welding wire and the workpiece surface should be 70-90°, and the horizontal angle between the welding torch and the workpiece should be 80-95°. After the root pass welding is completed and inspected for any welding defects, proceed with the overlay welding. The welding sequence is the same as the root pass. The weld overlay must be fused to the T-shaped inner sleeve and the interpass temperature must be controlled to ensure that the outer side of the T-shaped inner sleeve body does not melt in order to protect the threads. No welding defects should be generated between each layer of the weld overlay. After the weld overlay extends to the outside of the threaded hole, the horizontal angle between the welding wire and the surface of the workpiece should be 20-35°, and the horizontal angle between the welding gun and the workpiece should be 70-85°. Ensure that the welding wire is fed evenly so that the overall welded screw extension workpiece is cylindrical and firmly connected to the inner side of the T-shaped inner sleeve.

[0022] 2.3) When the top of the screw extension weldment to be welded is close to the top of the T-shaped inner sleeve, use an angle grinder to grind the outer side of the weld overlay layer, and then place the matching nut on the top surface of the T-shaped inner sleeve so that the matching nut and the T-shaped inner sleeve correspond. Then continue welding the screw extension weldment. The bottom layer weld is fused to the welded cylindrical upper surface of the screw extension weldment, and the weld overlay layer is fused to the inner side of the matching nut. The welding method, welding sequence, and welding angle are the same as the bottom layer weld, so that the screw extension weldment finally formed is firmly connected to the top of the broken bolt rod and the inner side of the T-shaped inner sleeve and the matching nut respectively.

[0023] 2.4) After all welding is completed, allow it to cool. Finally, use a regular adjustable wrench to tighten the matching nut without damaging the main body. Then, rotate the screw rod counterclockwise to extend the welded part and remove it together with the T-shaped inner sleeve and the broken screw rod for use.

[0024] Furthermore, the welding equipment is a digitally controlled inverter manual DC argon arc welding machine of model HT400D or HT500D.

[0025] Furthermore, when welding the root pass, ER50-6 welding wire with a diameter of 2.0mm is used, the welding current is 90-130A, the arc voltage is 24±1V, and the tungsten electrode diameter is 2.0mm; when welding the overlay layer, ER50-6 welding wire with a diameter of 3.0mm is used, the welding current is 140-160A, the arc voltage is 26±1V, and the tungsten electrode diameter is 2.5mm.

[0026] Compared with existing technologies, the welding structure and supporting welding process for removing broken screws from the manhole body of a ball mill described in this invention are easy to implement, have stable welding quality, and low investment costs. Without damaging the ball mill cylinder body, the broken screw can be easily removed from the threaded hole, meeting the actual needs of the site, with high work efficiency, effectively reducing long-term downtime losses, and providing a strong guarantee for the rational production of ball mills. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the connection of the manhole cover plate on the ball mill cylinder in this invention;

[0028] Figure 2 This is a schematic diagram of the broken screw rod inside the threaded hole in this invention;

[0029] Figure 3 This is a schematic diagram of the welding structure in this invention;

[0030] Figure 4 This is a welding schematic diagram of the screw extension weldment in this invention;

[0031] In the diagram: 1. Matching nut; 2. Screw extension welded part; 3. Ball mill cylinder; 4. Broken screw; 5. T-shaped inner sleeve; 6. Thread; 7. Manhole cover; 8. Locking screw; 9. Threaded hole. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this disclosure pertains. The terms "upper," "lower," "left," "right," "front," and "back" used in the present patent application specification and claims are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship also changes accordingly. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Any aspects not detailed in this invention are well-known to those skilled in the art.

[0033] Example 1:

[0034] like Figures 1 to 3 As shown, the present invention discloses a welded structure for removing a broken screw from the manhole body of a ball mill. The ball mill includes a ball mill cylinder 3, on which a manhole is provided and multiple threaded holes 9 are provided along the edge of the manhole. The inner side of the threaded holes 9 is provided with threads 6 for installing locking screws 8. The manhole cover plate 7 is installed on the ball mill cylinder 3 by means of locking screws 8. After long-term operation of the ball mill, several locking screws 8 break, forming broken screws 4 with their tops lower than the opening of the threaded hole 9. The broken screws 4 are threaded inside the threaded hole 9. To facilitate the removal of the broken screws 4, a welding structure is designed. This structure includes a T-shaped inner sleeve 5, a screw extension welding piece 2, and a matching nut 1. The T-shaped inner sleeve 5 is set inside the threaded hole 9, with its bottom abutting against the top of the broken screw 4, and the matching nut 1 is set on its top. The screw extension welding piece 2 is set inside the inner hole of the T-shaped inner sleeve 5 and the matching nut 1. It is welded by manual argon arc welding using welding wire, and its bottom and outer side are welded and fixed to the top of the broken screw 4 and the inner side of the T-shaped inner sleeve 5 and the matching nut 1, respectively.

[0035] When applying the solution, clean the stains on the top of the broken screw 4 and polish it to expose the metallic luster. Restore the threads 6 of the threaded hole 9 on the top of the broken screw 4. Then, install the T-shaped inner sleeve 5 in the threaded hole 9. Weld the screw extension weldment 2 so that the outer side and bottom of the screw extension weldment 2 are fused together with the T-shaped inner sleeve 5 and the top of the broken screw 4, respectively. Set the matching nut 1 on the top surface of the T-shaped inner sleeve 5. Then, continue to weld the screw extension weldment 2 so that the outer side of the screw extension weldment 2 is firmly welded to the matching nut 1. Then, use a regular adjustable wrench to tighten the matching nut 1 without damaging the main body. Then, rotate the screw extension weldment 2 counterclockwise and remove it together with the T-shaped inner sleeve 5 and the broken screw 4 from the threaded hole 9.

[0036] In this embodiment, the T-shaped inner sleeve 5 is machined from a steel pipe. Its outer diameter is smaller than that of the broken screw rod 4, and its wall thickness is 1.5 to 2 mm. It is attached to the outside of the thread 6 to prevent the thread 6 from being damaged during welding. In addition, the T-shaped inner sleeve 5 is placed vertically on the upper surface of the broken screw rod 4 and is welded together with the screw rod extension welding part 2 during welding.

[0037] In this embodiment, the matching nut 1 is machined from round steel. The inner diameter of the matching nut 1 is larger than the outer diameter of the screw extension welded part 2, which can meet the requirements for welding and installation on the screw extension welded part 2. The outer shape of the matching nut 1 is a hexagonal cube, and any two planes can accommodate the insertion of a conventional adjustable wrench, which is convenient for disassembly.

[0038] In this embodiment, the inner diameter of the T-shaped inner sleeve 5 is the same as that of the matching nut 1, which facilitates welding connection with the screw extension welding part 2.

[0039] Example 2:

[0040] like Figure 1-4 As shown, this invention discloses a welding process for removing broken screws from the manhole body of a ball mill, corresponding to the welding structure described in Embodiment 1. The ball mill includes a ball mill cylinder 3, on which a manhole is provided, and multiple threaded holes 9 are provided along the edge of the manhole for installing a manhole cover 7 via locking screws 8. Threads 6 are provided inside the threaded holes 9 and connected to the locking screws 8. Several locking screws 8 break, forming broken screws 4 with their tops lower than the openings of the threaded holes 9. The top of the broken screws 4 is cleaned of dirt and polished to expose a metallic luster, restoring the threaded holes 9 above the broken screws 4. 6. Then install the T-shaped inner sleeve 5 in the threaded hole 9, weld the screw extension weld 2 so that the outer side and bottom of the screw extension weld 2 are fused together with the T-shaped inner sleeve 5 and the top of the broken screw 4 respectively. Set the matching nut 1 on the top surface of the T-shaped inner sleeve 5, then continue to weld the screw extension weld 2 so that the outer side of the screw extension weld 2 is firmly welded to the matching nut 1. Then use a conventional adjustable wrench to tighten the matching nut 1 without damaging the body, and then rotate the screw extension weld 2 counterclockwise and remove it together with the T-shaped inner sleeve 5 and the broken screw 4 from the threaded hole 9.

[0041] The specific steps are as follows:

[0042] Step 1: Preparation before welding

[0043] 1.1) Welding equipment: HT400D or HT500D digital control inverter manual DC TIG welding machine, using ER50-6 welding wire;

[0044] 1.2) Welding position: Flat welding;

[0045] 1.3) Pre-welding requirements: The welding area must be free of oil, oxide layer and moisture, and must show a metallic luster;

[0046] 1.4) Welding technical requirements: The weld overlay layer must be fused to protect the inner thread of the threaded sleeve and the bottom layer;

[0047] 1.5) Welding material: Grade 8.8 high-strength screw;

[0048] 1.6) Auxiliary facilities: templates, magnifying glasses, face masks, gloves, slag removal hammers, hammers, chisels, files, wire brushes, sandpaper, steel rulers, spirit levels, adjustable wrenches, straight grinders, angle grinders, wire cutters, hacksaw blades, personal protective equipment (work clothes, shoes, hats, non-optical glasses);

[0049] 1.7) Welding process parameters: Welding parameters are determined based on the welding equipment, welding materials, workpiece material, and welding requirements;

[0050] Manual TIG welding process parameters

[0051] Electrode type weld layer Electrode diameter / mm Welding current A Arc voltage / V Tungsten electrode diameter ER50-6 Start from the bottom φ2.0mm 90-130 24±1 φ2.0mm ER50-6 weld overlay φ3.0mm 140-160 26±1 φ2.5mm

[0052] Step Two: Implementation:

[0053] 2.1) Rotate the ball mill cylinder 3 to a horizontal position at the location of the broken screw 4. Use an oxy-acetylene flame to remove moisture, oil, and other stains at the location of the broken screw 4. Then, use sandpaper or a grinding wheel to remove rust. Next, use an angle grinder to clean the top of the broken screw 4. After the upper surface of the broken screw 4 is ground smooth and shiny, use manual mechanical tools to restore the threads 6 on the upper part of the threaded hole 9. Then, install a T-shaped inner sleeve 5 that fits the threaded hole 9, ensuring that the bottom of the T-shaped inner sleeve 5 is in contact with the top of the broken screw 4. Finally, use a digitally controlled inverter manual DC argon arc welding machine to weld the screw extension welding part 2.

[0054] 2.2) When welding the bottom layer, start from the junction of the T-shaped inner sleeve 5 and the top of the broken screw 4, and operate the welding in a circular pattern from the outside to the inside (e.g., Figure 3 and 4The welding sequence for welds 1'-4' is shown below. After the arc is ignited, preheat the workpiece for 3-5 seconds at the starting point to form a molten pool. Then, start feeding the wire. The welding method is a small crescent shape. Because the welding wire and torch are welded inside the threaded hole 9, the horizontal angle between the welding wire and the workpiece surface is 70-90°, and the horizontal angle between the torch and the workpiece is 80-95°. After the root pass welding is completed and inspected for any welding defects, proceed with the overlay welding, following the same welding sequence as the root pass (e.g., ...). Figure 3 For the intermediate weld seam 5' to 16'), the weld overlay layer must be fused well with the T-shaped inner sleeve 5 and the interpass temperature must be controlled to ensure that the outer side of the T-shaped inner sleeve 5 body does not melt in order to protect the thread 6. No welding defects should be generated between the layers of the weld overlay layer. After the weld overlay layer is extended to the outside of the threaded hole 9, that is, when the welding gun and other equipment can be operated outside the threaded hole, the horizontal angle between the welding wire and the surface of the workpiece is 20-35°, and the horizontal angle between the welding gun and the workpiece is 70-85°. Ensure that the welding wire is fed evenly so that the overall welded screw extension welded part 2 is cylindrical and firmly connected to the inner side of the T-shaped inner sleeve 5.

[0055] 2.3) When the top of the screw extension welding part 2 to be welded is close to the top of the T-shaped inner sleeve 5, use an angle grinder to grind the outer side of the weld overlay, then place the matching nut 1 on the top surface of the T-shaped inner sleeve 5 so that the matching nut 1 and the T-shaped inner sleeve 5 correspond, and then continue welding the screw extension welding part 2 (e.g. Figure 3 The middle weld (17'~24') is welded to the cylindrical upper surface of the welded screw extension welded part 2 after the bottom layer is welded, and the weld overlay layer is welded to the inner side of the matching nut 1. The welding method, welding sequence, and welding angle are the same as the bottom layer weld, so that the screw extension welded part 2 formed by the final weld is firmly connected to the top of the broken bolt rod 4 and the T-shaped inner sleeve 5 and the inner side of the matching nut 1 respectively.

[0056] 2.4) After all welding is completed, allow it to cool. Finally, use a regular adjustable wrench to tighten the matching nut 1 without damaging the main body. Then, rotate the screw extension welded part 2 counterclockwise and remove it together with the T-shaped inner sleeve 5 and the broken screw 4 for use.

Claims

1. A welded structure for removing a broken screw from a manhole body of a ball mill, the ball mill comprising a ball mill cylinder (3), a manhole being provided on the ball mill cylinder (3) and multiple threaded holes (9) being provided along the edge of the manhole, threads (6) being provided inside the threaded holes (9), and several broken screws (4) with their tops lower than the openings of the threaded holes (9) being threadedly connected to the inside of the threaded holes (9), characterized in that: The welding structure includes a T-shaped inner sleeve (5), a screw extension welding piece (2), and a matching nut (1); the T-shaped inner sleeve (5) is set in the threaded hole (9), its bottom abuts against the top of the broken screw (4), and the matching nut (1) is set on its top; the screw extension welding piece (2) is set in the inner hole of the T-shaped inner sleeve (5) and the matching nut (1), it is welded by welding wire, and its bottom and outer side are welded and fixed to the top of the broken screw (4) and the inner side of the T-shaped inner sleeve (5) and the matching nut (1), respectively; The T-shaped inner sleeve (5) is machined from steel pipe, and its outer diameter is smaller than that of the broken screw (4), and its wall thickness is 1.5~2mm. The matching nut (1) is made of round steel by machining.

2. The welded structure for removing a broken screw from the manhole body of a ball mill according to claim 1, characterized in that: The inner diameter of the T-shaped inner sleeve (5) is the same as that of the matching nut (1).

3. A welding process for removing broken screws from the manhole body of a ball mill, wherein the ball mill includes a ball mill cylinder (3), a manhole is provided on the ball mill cylinder (3), and multiple threaded holes (9) are provided on the edge of the manhole for installing a manhole cover plate (7) through locking screws (8), the threaded holes (9) are provided with threads (6) on the inner side and connected to the locking screws (8), and several locking screws (8) break to form broken screws (4) with their tops lower than the openings of the threaded holes (9), characterized in that: Clean the stains on the top of the broken screw (4) and polish it to reveal the metal luster. Restore the threads (6) of the threaded hole (9) above the broken screw (4). Then install the T-shaped inner sleeve (5) in the threaded hole (9). Weld the screw extension welding part (2) so that the outer side and bottom of the screw extension welding part (2) are fused together with the T-shaped inner sleeve (5) and the top of the broken screw (4) respectively. Set the matching nut (1) on the top surface of the T-shaped inner sleeve (5). Then continue to weld the screw extension welding part (2) so that the outer side of the screw extension welding part (2) is firmly welded to the matching nut (1). Then tighten the matching nut (1) with a regular adjustable wrench without damaging the body. Then rotate the screw extension welding part (2) counterclockwise and take it out of the threaded hole (9) together with the T-shaped inner sleeve (5) and the broken screw (4).

4. The welding process for removing a broken screw from the manhole body of a ball mill according to claim 3, characterized in that: The specific method for removing the broken screw (4) is as follows: Step 1: Preparation before welding 1.1) Welding equipment: Digitally controlled inverter manual DC TIG welding machine, using ER50-6 welding wire; 1.2) Welding position: Flat welding; 1.3) Pre-welding requirements: The welding area must be free of oil, oxide layer and moisture, and must show metallic luster; 1.4) Welding technical requirements: The weld overlay layer must be fused to protect the inner thread of the threaded sleeve and the bottom layer; 1.5) Welding material: Grade 8.8 high-strength screw; 1.6) Auxiliary facilities: templates, magnifying glasses, face masks, gloves, slag removal hammers, hammers, chisels, files, wire brushes, sandpaper, steel rulers, spirit levels, adjustable wrenches, straight grinders, angle grinders, wire cutters, hacksaw blades, personal protective equipment; 1.7) Welding process parameters: Welding parameters are determined based on the welding equipment, welding materials, workpiece material, and welding requirements; Step Two: Implementation: 2.1) Rotate the ball mill cylinder (3) to a horizontal position at the location of the broken screw (4), use an oxy-acetylene flame to remove the moisture and oil at the location of the broken screw (4), then use sandpaper or a grinding wheel to grind away the rust, and then use an angle grinder to clean the top of the broken screw (4). After the upper surface of the broken screw (4) is ground flat and shiny, use a manual mechanical tool to restore the threads (6) on the upper part of the threaded hole (9), and then install a T-shaped inner sleeve (5) that fits the threaded hole (9), ensuring that the bottom of the T-shaped inner sleeve (5) is in contact with the top of the broken screw (4), and then use a digitally controlled inverter manual DC argon arc welding machine to weld the screw extension welding part (2). 2.2) When welding the root pass, start from the junction of the T-shaped inner sleeve (5) and the top of the broken screw (4). The welding sequence is to operate in a circular pattern from the outside to the inside. After the arc is ignited, preheat the workpiece for 3-5 seconds at the starting point. After forming a molten pool, start feeding the wire. The welding method is a small crescent shape. Because the welding wire and welding gun are welded inside the threaded hole (9), the horizontal angle between the welding wire and the workpiece surface is 70-90°, and the horizontal angle between the welding gun and the workpiece is 80-95°. After the root pass welding is completed and no welding defects are detected, the overlay welding is performed. The welding sequence is the same as the previous one. The bottom layer is consistent, the weld overlay layer must be fused well with the T-shaped inner sleeve (5) and the interlayer temperature must be controlled to ensure that the outer side of the T-shaped inner sleeve (5) body does not melt to protect the thread (6). No welding defects should be generated between each layer of the weld overlay layer. After the weld overlay layer is extended to the outside of the threaded hole (9), the horizontal angle between the welding wire and the surface of the workpiece is 20-35°, and the horizontal angle between the welding gun and the workpiece is 70-85° to ensure that the welding wire is fed evenly, so that the overall welded screw extension welded part (2) is cylindrical and firmly connected to the inner side of the T-shaped inner sleeve (5). 2.3) When the top of the screw extension welding part (2) to be welded is close to the top of the T-shaped inner sleeve (5), use an angle grinder to grind the outer side of the weld overlay layer, and then place the matching nut (1) on the top surface of the T-shaped inner sleeve (5) so that the matching nut (1) and the T-shaped inner sleeve (5) correspond to each other. Then continue the welding of the screw extension welding part (2). The bottom layer welds the cylindrical upper surface of the screw extension welding part (2) that has been welded, and the weld overlay layer welds the inner side of the matching nut (1). The welding method, welding sequence, and welding angle are the same as the bottom layer welding, so that the screw extension welding part (2) formed by the final welding is firmly connected to the top of the broken screw (4) and the inner side of the T-shaped inner sleeve (5) and the matching nut (1); 2.4) After all welding is completed, cool it down. Finally, use a regular adjustable wrench to tighten the matching nut (1) without damaging the body. Then rotate the screw to extend the welded part (2) in the counterclockwise direction and take it out together with the T-shaped inner sleeve (5) and the broken screw (4) for use.

5. The welding process for removing a broken screw from the manhole body of a ball mill according to claim 4, characterized in that: The welding equipment is a digitally controlled inverter manual DC argon arc welding machine of model HT400D or HT500D.

6. The welding process for removing a broken screw from the manhole body of a ball mill according to claim 4, characterized in that: For the root pass welding, use ER50-6 welding wire with a diameter of 2.0mm, welding current of 90~130A, arc voltage of 24±1V, and tungsten electrode diameter of 2.0mm; for the overlay welding, use ER50-6 welding wire with a diameter of 3.0mm, welding current of 140~160A, arc voltage of 26±1V, and tungsten electrode diameter of 2.5mm.

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