Method for forming a forged and welded structure split gear rim

Abstract

A method for forming a forged and welded split gear rim involves forging a full circular ring using a large ring rolling mill and cutting it into two semi-circular rings. Radial extrusion using hydraulic jacks and a square box prevents radius expansion after the full circle is cut, reducing the radius of the semi-circular rings to their pre-welding radius. A tie rod fixture then fixes the reduced-diameter, straightened semi-circular rings, allowing for heat treatment while maintaining the radius dimensions. Finally, removing the tie rod fixture and machining the components allows the two semi-circular rings to be welded into a full circular rim. This method eliminates the need for large plate rolling machines to bend steel plates into arc shapes and for extending the ends of the steel plate as clamps. Therefore, it reduces costs in terms of both equipment and materials used. This simplifies the production process, enabling manufacturers without large plate rolling machines or access to large quantities of high-strength steel plates to produce forged and welded split gear rims.

Description

Technical Field

[0001] This invention relates to the field of manufacturing methods for forged and welded split gears, and more particularly to a method for forming the rim of a forged and welded split gear. Background Technology

[0002] Split gears are core components of large equipment such as mills, rotary kilns, and mixers, and are typically manufactured from cast steel. As equipment sizes continue to increase, the performance and hardness requirements for gear materials are also rising. Simultaneously, stringent national environmental policies have made the casting industry, which generates solid waste and air pollution during production, highly susceptible to policy impacts. Cleaner welding technologies are more aligned with these policies. With continuous breakthroughs in welding technology, numerous domestic and international companies have designed and developed forged-welded split gears. These gears utilize forged rims, resulting in refined grains, dense structure, and reduced stress concentration. The forged rims exhibit good plasticity and toughness, resistance to pitting, fatigue, and impact. The gears also boast high load-bearing capacity and high reliability.

[0003] Currently, wheel flanges are mainly manufactured by rolling high-strength steel plates. The high-strength steel plate is rolled into an arc shape using a plate rolling machine, and then the two ends of the arc are welded together. This method requires a large plate rolling machine and high-strength steel plates, but both large vertical plate rolling machines and high-strength steel plates are difficult to obtain and costly. Furthermore, due to welding requirements, both ends of the high-strength steel plate need to be extended as clamps to ensure the flange arc length, further resulting in material waste and increased costs. Summary of the Invention

[0004] The purpose of this invention is to provide a forming method for splitting the rim of a large gear using a forged and welded structure, which eliminates the need for a large plate rolling machine, saving materials and reducing costs.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a forming method for a forged and welded structure of a split large gear rim, comprising the following steps: Step 1: Forge a complete circular ring using a large ring rolling mill. After rough machining and ultrasonic testing of the complete circular ring, cut it into two semi-circular rings on average, ensuring that the radius of the semi-circular rings is greater than the machining dimension of the rim. Step 2: Perform diameter reduction and straightening on the semi-circular ring. Place the semi-circular ring flat on the ground beam platform and fix two square boxes on the ground beam platform. The two square boxes are located at the two ends of the arc of the semi-circular ring. One square box is in contact with the outer arc surface of the semi-circular ring near the opening on one side. A hydraulic jack is placed between the other square box and the semi-circular ring. One end of the hydraulic jack is pressed tightly against the square box, and the other end of the hydraulic jack is pressed tightly against the outer arc surface of the opening on the other side of the semi-circular ring. Then, the two ends of the semi-circular ring are radially compressed by extending the hydraulic jack, so that the radius of the semi-circular ring is reduced to the pre-welding radius. Step 3: While maintaining the extrusion of the semi-circular ring part in Step 2, weld the tie rod fixture onto the semi-circular ring part, then stop the extrusion and remove the hydraulic jack and square box. The tie rod fixture includes two transverse rods and two longitudinal rods. The two transverse rods are parallel to each other and spaced apart along the thickness direction of the semicircular ring. The outer walls of the two sides of the transverse rods along the length direction are welded to the tangential surfaces of the two ends of the arc of the semicircular ring. The two ends of the transverse rods along the length direction extend from the outer arc surfaces of the openings on both sides of the semicircular ring. Connecting plates are welded to the middle of the two transverse rods. The two connecting plates are spaced apart along the thickness direction of the semicircular ring, and a connecting rod is welded between the two connecting plates. The two longitudinal rods are parallel to each other and located on both sides of the two transverse rods along the thickness direction of the semicircular ring. The longitudinal rods are perpendicular to the transverse rods. The outer wall of one side of the longitudinal rod along the length direction is welded to the side wall of the arc apex of the semicircular ring, and the outer wall of the other side of the longitudinal rod along the length direction is welded to the connecting plate. Step 4: Heat treat the semi-circular ring after welding the tie rod fixture in Step 3. After heat treatment, remove the tie rod fixture, then machine the semi-circular ring to the pre-welding dimensions. Finally, weld the two semi-circular rings together to form a rim with a complete circular structure.

[0006] Preferably, the transverse rods, longitudinal rods, and connecting rods are all round rods with a diameter of 10 mm, and the connecting plate is a rectangular flat plate.

[0007] Preferably, one end of the longitudinal rod extends from the outer arc surface at the apex of the semicircular ring.

[0008] According to the above technical solution, the beneficial effects of the present invention are: This invention employs a large ring rolling mill to forge a complete circular ring and then cuts it into two semi-circular rings. After radial compression using hydraulic jacks and a square box, the radius expansion after cutting the complete circle is avoided, reducing the radius of the semi-circular rings to their pre-welding radius. A tie rod fixture then fixes the reduced-diameter, straightened semi-circular rings, allowing for heat treatment while maintaining the radius dimensions. Finally, after removing the tie rod fixture and further machining, the two semi-circular rings can be welded into a complete circular rim. Therefore, this invention utilizes a cutting and welding method, eliminating the need for large plate rolling machines to bend steel plates into arc shapes and for extending the ends of the steel plate as clamps. This reduces costs in terms of both equipment and materials, enabling manufacturers without large plate rolling machines and those struggling to obtain large quantities of high-strength steel plates to produce forged and welded split gear rims, simplifying the existing production process. Attached Figure Description

[0009] Figure 1 A schematic diagram of the welding process tie rod; Figure 2 for Figure 1 The corresponding front view diagram.

[0010] The markings in the diagram are: 1. Horizontal bar, 2. Vertical bar, 3. Connecting plate, 4. Connecting bar. Detailed Implementation

[0011] The embodiment is a forming method for a forged and welded structure of a split large gear rim, including the following steps: Step 1: Forge a complete circular ring using a large ring rolling mill. After rough machining and ultrasonic testing of the complete circular ring, cut it into two semi-circular rings, ensuring that the radius of the semi-circular rings is greater than the machining dimension of the rim.

[0012] Step 2: Perform diameter reduction and straightening on the semi-circular ring. Place the semi-circular ring flat above the ground beam platform and fix two square boxes on the platform. The two square boxes are located at the two ends of the arc of the semi-circular ring. One square box is in contact with the outer arc surface of the semi-circular ring near the opening on one side. A hydraulic jack is placed between the other square box and the semi-circular ring. One end of the hydraulic jack is pressed tightly against the square box, and the other end of the hydraulic jack is pressed tightly against the outer arc surface of the opening on the other side of the semi-circular ring. Then, by extending the hydraulic jack, the two ends of the semi-circular ring are radially compressed, so that the radius of the semi-circular ring is reduced to the pre-welding radius.

[0013] Step 3: While maintaining the compression of the semi-circular ring part in Step 2, weld the tie rod fixture onto the semi-circular ring part.

[0014] like Figure 1 , 2As shown, the tie rod fixture includes two transverse rods 1 and two longitudinal rods 2. The two transverse rods 1 are parallel to each other and are distributed at intervals along the thickness direction of the semicircular ring. The outer walls of the two sides of the transverse rod 1 in the length direction are welded to the tangent surfaces of the two ends of the arc direction of the semicircular ring, and the two ends of the transverse rod 1 in the length direction extend from the outer arc surface of the opening position on both sides of the semicircular ring.

[0015] Connecting plates 3 are welded to the middle of the two transverse rods 1 respectively. The two connecting plates 3 are spaced apart along the thickness direction of the semi-circular ring. A connecting rod 4 is welded between the two connecting plates 3.

[0016] Two longitudinal rods 2 are parallel to each other and located on both sides of the two transverse rods 1 along the thickness direction of the semicircular ring. The longitudinal rods 2 and the transverse rods 1 are perpendicular to each other. One side of the outer wall of the longitudinal rod 2 along its length direction is welded to the side wall of the arc apex of the semicircular ring, and this end extends from the outer arc surface of the arc apex of the semicircular ring. The other side of the outer wall of the longitudinal rod 2 along its length direction is welded to the connecting plate 3.

[0017] The transverse rod 1, longitudinal rod 2, and connecting rod 4 are all round rods with a diameter of 10 mm, and the connecting plate 3 is a rectangular flat plate. After the tie rod fixture is welded in place, stop pressing the semi-circular ring part, and remove the hydraulic jack and square box.

[0018] Step 4: Heat treat the semi-circular ring after welding the tie rod fixture in Step 3. After heat treatment, remove the tie rod fixture, then machine the semi-circular ring to the pre-welding dimensions. Finally, weld the two semi-circular rings together to form a rim with a complete circular structure.

[0019] Because of the adoption of a split-welding method, it is no longer necessary to use a large plate rolling machine to roll the steel plate into an arc shape, nor is it necessary to extend the steel plate at both ends as clamps. Therefore, both the equipment used and the materials consumed can be reduced in terms of cost. This allows manufacturers who do not have large plate rolling machines and have difficulty obtaining high-strength steel plates in large quantities to produce forged and welded split gear rims, simplifying the existing production process. An example was used to produce an 8-meter diameter rim. The calculated diameter shrinkage of this rim was 60mm. Finite element analysis showed that the required deformation load was only 29.5t; the maximum stress value of the deformed workpiece was approximately 64MPa; the maximum deviation between the deformed rim and the ideal model was 4mm. A 100-ton hydraulic jack was used to perform diameter reduction and straightening. The entire straightening process was smooth, without abnormal noise or deformation, and the rim was successfully compressed into place. Subsequently, the welding process was followed by reinforcement and performance heat treatment. After heat treatment, the reinforcement was removed, and the workpiece showed no springback, indicating good shaping effect.

Claims

1. A method for forming the rim of a forged and welded split large gear, characterized in that, Includes the following steps: Step 1: Forge a complete circular ring using a large ring rolling mill. After rough machining and ultrasonic testing of the complete circular ring, cut it into two semi-circular rings on average, ensuring that the radius of the semi-circular rings is greater than the machining dimension of the rim. Step 2: Perform diameter reduction and straightening on the semi-circular ring. Place the semi-circular ring flat on the ground beam platform and fix two square boxes on the ground beam platform. The two square boxes are located at the two ends of the arc of the semi-circular ring. One square box is in contact with the outer arc surface of the semi-circular ring near the opening on one side. A hydraulic jack is placed between the other square box and the semi-circular ring. One end of the hydraulic jack is pressed tightly against the square box, and the other end of the hydraulic jack is pressed tightly against the outer arc surface of the opening on the other side of the semi-circular ring. Then, the two ends of the semi-circular ring are radially compressed by extending the hydraulic jack, so that the radius of the semi-circular ring is reduced to the pre-welding radius. Step 3: While maintaining the extrusion of the semi-circular ring part in Step 2, weld the tie rod fixture onto the semi-circular ring part, then stop the extrusion and remove the hydraulic jack and square box. The tie rod fixture includes two transverse rods (1) and two longitudinal rods (2). The two transverse rods (1) are parallel to each other and are spaced apart along the thickness direction of the semicircular ring. The outer walls of the two sides of the transverse rods (1) along the length direction are welded to the tangent surfaces of the two ends of the arc direction of the semicircular ring. The two ends of the transverse rods (1) along the length direction extend from the outer arc surfaces of the opening positions on both sides of the semicircular ring. The middle part of the two transverse rods (1) is welded with connecting plates (3). The two connecting plates (3) are spaced apart along the thickness direction of the semicircular ring. A connecting rod (4) is welded between the two connecting plates (3). The two longitudinal rods (2) are parallel to each other and are located on both sides of the two transverse rods (1) along the thickness direction of the semicircular ring. The longitudinal rods (2) are perpendicular to the transverse rods (1). The outer wall of one side of the longitudinal rod (2) along the length direction is welded to the side wall of the arc top position of the semicircular ring. The outer wall of the other side of the longitudinal rod (2) along the length direction is welded to the connecting plate (3). Step 4: Heat treat the semi-circular ring after welding the tie rod fixture in Step 3. After heat treatment, remove the tie rod fixture, then machine the semi-circular ring to the pre-welding dimensions. Finally, weld the two semi-circular rings together to form a rim with a complete circular structure.

2. The forming method for a forged and welded structure of a split large gear rim according to claim 1, characterized in that: The transverse rod (1), longitudinal rod (2) and connecting rod (4) are all round rods with a diameter of 10 mm, and the connecting plate (3) is a rectangular flat plate.

3. The forming method for a forged and welded structure of a split large gear rim according to claim 1, characterized in that: One end of the longitudinal rod (2) extends from the outer arc surface at the top of the semi-circular ring along its length.

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