A fixture for fixing longitudinal seam welding of cylinder body

Abstract

This utility model discloses a welding and fixing fixture for longitudinal seams of a cylinder, including a cylinder with longitudinal seams and two U-shaped clamps. Both the inner and outer walls of the longitudinal seams have bevels, and both U-shaped clamps have horizontal grooves. The longitudinal seams at both ends of the cylinder are placed within their respective grooves. An outer arc plate and a pressure plate are sequentially arranged above the cylinder. A liner is provided within the bevel of the outer wall of the longitudinal seam. Both ends of the pressure plate and the outer arc plate are placed within their respective grooves. Several clamping screws are provided on each U-shaped clamp above the grooves. The lower ends of the clamping screws pass through the pressure plate and contact the outer arc plate. The pressure plate has several central clamping screws. Inner arc plates located below both ends of the cylinder are provided in both grooves. The inner arc plate below the longitudinal seams and the U-shaped clamps have connected longitudinal through grooves. This utility model can ensure that the cylinder diameter meets the precise requirements of the drawings or the maximum positive tolerance requirements of the internal component assembly, greatly reduces the workload of reverse side cleaning, and also improves assembly efficiency and fixture reusability.

Description

Technical Field

[0001] This utility model relates to a welding and fixing fixture for longitudinal seams of a cylinder, and more particularly to a welding and fixing fixture for longitudinal seams of a cylinder that ensures the diameter of the cylinder meets tolerance requirements after welding. Background Technology

[0002] Thin-walled boiler and pressure vessel cylinders (generally δ≤40mm) are typically manufactured using a process where steel plates are machined with longitudinal bevels according to drawings, rolled into cylinders, and then welded. Due to the product's structural characteristics, the cylinder diameter must be close to the maximum positive tolerance to ensure smooth assembly with internal components, or to meet the precise diameter tolerance control requirements specified in the drawings. However, during processing, the outer cylinder is typically cut into multiple sections based on its mean diameter. After rolling, the longitudinal seam welding often makes it difficult to precisely control the cylinder diameter due to thermal shrinkage stress. Furthermore, variations in steel plate material, thickness, welding parameters, operator experience, and environment can lead to the cylinder diameter after longitudinal seam welding not meeting the maximum positive tolerance requirements for assembly, resulting in difficulties in assembling internal components. Therefore, for products with strict requirements in drawings or where precise control of the cylinder diameter is necessary for internal component assembly, the common solution is to leave a gap during longitudinal seam welding, especially for products with high thermal shrinkage stress during longitudinal seam welding of nickel alloy and stainless steel cylinders.

[0003] For cylinder bodies with longitudinal seams welded using an X-groove, the commonly used solution is as follows: Option 1: When assembling the product's cylindrical body with tooling, leave a gap according to the maximum positive tolerance before welding; Option 2: When assembling the longitudinal seam of the product cylinder, use flat steel of the same or similar material as the cylinder body. Process it to match the size of the inner wall bevel surface of the cylinder body after leaving the gap, and fill the outer side of the longitudinal seam with spot welding to fix it, as shown in c. After the longitudinal seam of the inner wall of the cylinder body is welded, thoroughly remove the flat steel from the reverse side and then weld the outer wall.

[0004] The problems with the above two solutions are as follows: Option 1 is insufficient to resist the thermal shrinkage stress generated during the longitudinal seam welding process of the cylinder due to the insufficient external force of the tooling. This results in the reserved gap between the longitudinal seam bevel surfaces becoming smaller or disappearing, making it impossible to accurately guarantee the reserved gap between the longitudinal seam bevel surfaces. At the same time, if the gap is too large, problems such as the inability to weld the longitudinal seam or poor weld formation with many defects may occur. Although Option 2 can ensure that the gap between the longitudinal seam bevels does not disappear due to thermal shrinkage stress during the longitudinal seam welding process by spot welding the filler flat steel to the outer wall of the cylinder, it has drawbacks. After the outer wall bevel is welded, when cleaning the root of the outer wall, since the flat steel has fused with the inner wall weld, to completely remove the flat steel, a portion of the weld must also be removed. This not only results in a huge workload and low production efficiency for root cleaning, but also requires the removal of part of the welded seam to ensure thorough root cleaning. Therefore, the outer wall bevel becomes larger after root cleaning, and the reserved gap between the longitudinal seam bevels decreases within a certain range due to welding thermal shrinkage stress during the outer wall welding. All of the above make it difficult to guarantee that the diameter of the cylinder meets the tolerance requirements after welding. Summary of the Invention

[0005] The purpose of this utility model is to address the above-mentioned shortcomings of the prior art by providing a welding fixture for longitudinal seams of cylinders. It can avoid the problems of reduced reserved gaps caused by welding heat shrinkage stress, excessive gaps between bevel surfaces, lack of support for the weld pool on the inner wall, inability to weld, or poor weld formation and many defects. This ensures that the cylinder diameter meets the precise requirements of the drawings or the maximum positive tolerance requirements of the internal parts assembly, greatly reduces the workload of back-side cleaning, and also improves assembly efficiency and fixture reuse rate.

[0006] To achieve the above objectives, this utility model provides a cylindrical body longitudinal seam welding and fixing fixture, comprising a cylindrical body with longitudinal seams and two U-shaped clamps. Both the inner and outer walls of the longitudinal seams are beveled, and the middle of the adjacent side of each of the two U-shaped clamps is provided with a horizontal groove. The fixture is characterized in that: the longitudinal seams at both ends of the cylindrical body are placed within their respective grooves; an outer arc plate and a pressure plate are sequentially arranged above the cylindrical body; the lower side of the outer arc plate is a concave arc surface; a liner is provided within the bevel of the outer wall of the longitudinal seam, and the liner matches the cross-sectional shape of the bevel; both ends of the pressure plate and the outer arc plate are placed within their respective grooves; each U-shaped clamp above the groove is provided with several clamping screws, the lower ends of which pass through the pressure plate and contact the outer arc plate; the pressure plate between the two U-shaped clamps is provided with several central clamping screws; each groove contains an inner arc plate located below both ends of the cylindrical body, the upper side of which is a convex arc surface; the inner arc plate below the longitudinal seam and the U-shaped clamps are provided with connected longitudinal through grooves.

[0007] The upper convex arc surface of the inner arc plate and the lower concave arc surface of the outer arc plate match the inner and outer wall arc surfaces of the cylinder body, respectively. The cylinder body on both sides of the longitudinal seam can be pressed and fixed between the inner and outer arc plates using clamping screws and a central clamping screw. A ceramic gasket is used, which is pressed into the outer wall bevel of the longitudinal seam to ensure a constant gap between the bevel surfaces. Welding is first performed on the inner wall bevel of the longitudinal seam of the cylinder body. Then, the U-shaped clamps at both ends, the outer arc plate, the pressure plate, the inner arc plate, and the ceramic gasket are removed. The outer wall bevel is cleaned, and welding is then performed on the outer wall bevel of the longitudinal seam of the cylinder body to complete the welding of the entire longitudinal seam. This utility model, due to the filling of ceramic gaskets between the bevel surfaces... Using ceramic gaskets and fixing them to the outer wall of the longitudinal seam bevel can avoid problems such as reduced reserved gaps caused by welding heat shrinkage stress, excessive gaps between bevel surfaces, lack of support for the inner wall welding pool, inability to weld, or poor weld formation and many defects. This ensures that the cylinder diameter meets the precise requirements of the drawings or the maximum positive tolerance requirements of the internal parts assembly. Since the ceramic gaskets do not fuse with the weld, after welding the inner wall, only the ceramic gaskets need to be knocked off and the weld bead needs to be slightly ground and cleaned before reverse welding can be performed, which greatly reduces the workload of reverse root cleaning. In addition, the tooling is detachable and reusable, making installation and removal convenient and quick. Fixing the ceramic gaskets is reliable and effective, and it can also improve assembly efficiency and tooling reuse rate. As a further improvement of this utility model, the inner arc plate is fixedly connected to two limiting baffles that cooperate with the U-shaped clamp on both sides in the width direction; this facilitates the positioning of the inner arc plate in the width direction and its assembly with the U-shaped clamp. As a further improvement of this utility model, the bottom of the groove of the two U-shaped clamps and the outer ends of the pressure plate and the inner arc plate are provided with matching rounded corners; this can reduce stress concentration at sharp corners. On the other hand, the two U-shaped clamps cooperate with the pressure plate and the inner arc plate to make the tooling more reliably fixed under force. In summary, this utility model can avoid the problems caused by reduced reserved gaps due to welding thermal shrinkage stress, excessive gaps between bevel surfaces, lack of support for the inner wall welding pool, inability to weld, or poor weld formation and numerous defects. This ensures that the cylinder diameter meets the precise requirements of the drawings or the maximum positive tolerance requirements of the internal parts assembly, greatly reduces the workload of back-side root cleaning, and also improves assembly efficiency and tooling reuse rate. Attached Figure Description

[0008] Figure 1 This is a front view of an embodiment of the present utility model.

[0009] Figure 2 for Figure 1 AA sectional view.

[0010] Figure 3 for Figure 2 Enlarged view of point Y.

[0011] Figure 4 for Figure 1 Front view of the U-shaped clamp. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings.

[0013] like Figures 1 to 4 As shown, this embodiment of a cylindrical body longitudinal seam welding and fixing fixture includes a cylindrical body 1 with a longitudinal seam 2, and two U-shaped clamps 3 and 4. The inner and outer walls of the longitudinal seam 2 are both provided with bevels, and the middle of the adjacent side of the two U-shaped clamps 3 and 4 is provided with a horizontal groove. The longitudinal seams 2 at both ends of the cylindrical body 1 are placed in the grooves of the two U-shaped clamps 3 and 4 respectively. The longitudinal seams 2 are located on the upper side of the cylindrical body 1. An outer arc plate 5 and a pressure plate 6 are arranged sequentially above the cylindrical body 1. The lower side of the outer arc plate 5 is a concave arc surface. A ceramic gasket 7 is provided in the bevel of the outer wall of the longitudinal seam 2. The cross-sectional shape of the gasket 7 matches that of the bevel of the outer wall and is trapezoidal. The two ends of the pressure plate 6 and the outer arc plate 5 are placed in the grooves of the two U-shaped clamps 3 and 4 respectively. The U-shaped clamps 3 and 4 above the groove are each threaded with several clamping screws 8. The lower ends of the clamping screws 8 pass through the pressure plate 6 and contact the outer arc plate 5. The pressure plate 6 between the two U-shaped clamps 3 and 4 is threaded with several central clamping screws 9. The two grooves are each provided with an inner arc plate 10 located below both ends of the cylinder body 1. The upper side of the inner arc plate 10 is a convex arc surface. The inner arc plate 10 is integrally fixed with a limiting baffle 11 that cooperates with the U-shaped clamp on both sides in the width direction. The inner arc plate 10 below the longitudinal seam 2 and the U-shaped clamps 3 or 4 are provided with a connected longitudinal through groove 12. The bottom of the grooves of the two U-shaped clamps 3 and 4 and the outer ends of the pressure plate 6 and the inner arc plate 10 are all provided with matching rounded corners R.

[0014] The upper convex arc surface of the inner arc plate 10 and the lower concave arc surface of the outer arc plate 5 are respectively matched with the inner and outer arc surfaces of the cylinder body 1. The cylinder body 1 on both sides of the longitudinal seam 2 can be pressed and fixed between the inner arc plate 10 and the outer arc plate 5 by the clamping screw 8 and the middle clamping screw 9. At the same time, the ceramic gasket 7 is also pressed into the outer wall bevel of the longitudinal seam 2 to ensure that the gap of the bevel surface remains unchanged. During welding, welding is first carried out on the inner wall bevel of the longitudinal seam 2. The inner wall bevel of the longitudinal seam 2 can be welded through the longitudinal through groove 12 by the U-shaped clamps 3 and 4. Then, the U-shaped clamps 3 and 4, the outer arc plate 5, the pressure plate 6, the inner arc plate 10, and the ceramic gasket 7 at both ends are removed, and the root of the outer wall bevel is cleaned. Then, welding is carried out on the outer wall bevel of the longitudinal seam 2 to complete the entire longitudinal seam. Welding of seam 2; This utility model, by filling the bevel surfaces with ceramic gasket 7 and fixing it to the outer wall of the longitudinal seam bevel, can avoid the problems of reduced reserved gap or excessive gap between bevel surfaces caused by welding heat shrinkage stress, resulting in no support for the weld pool of the inner wall welding, leading to the inability to weld or poor weld formation and many defects. This ensures that the cylinder diameter meets the precise requirements of the drawing or the maximum positive tolerance requirements of the internal parts assembly. Since the ceramic gasket 7 does not fuse with the weld, after welding the inner wall, only the ceramic gasket needs to be knocked off and the weld bead needs to be slightly ground and cleaned before reverse welding can be carried out, which greatly reduces the workload of reverse root cleaning. In addition, the tooling is detachable and reusable, and the installation and removal are convenient and quick. The ceramic gasket is reliably and effectively fixed, which can also improve the assembly work efficiency and tooling reuse rate. The limiting baffle 11 facilitates the positioning of the inner arc plate 10 in the width direction and its assembly with the U-shaped clamp; The rounded corner R can reduce stress concentration at sharp corners. On the other hand, the two U-shaped clamps 3 and 4 cooperate with the pressure plate 6 and the inner arc plate 10 through the rounded corners, so that the tooling is better fixed and more reliable in terms of force. The above embodiments have been used to illustrate the invention, but it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments.

Claims

1. A fixture for fixing longitudinal seam welding of a cylinder, comprising a cylinder with a longitudinal seam, two U-shaped clamps, wherein the inner and outer walls of the longitudinal seam are provided with bevels, and the middle of the adjacent side of each of the two U-shaped clamps is provided with a horizontal groove; characterized in that: The longitudinal seams at both ends of the cylinder are placed in their respective grooves. An outer arc plate and a pressure plate are arranged sequentially above the cylinder. The lower side of the outer arc plate is a concave arc surface. A liner is provided in the bevel of the outer wall of the longitudinal seam. The liner matches the cross-sectional shape of the bevel of the outer wall. Both ends of the pressure plate and the outer arc plate are placed in their respective grooves. The U-shaped clamps above the grooves are provided with several clamping screws. The lower ends of the clamping screws pass through the pressure plate and contact the outer arc plate. The pressure plate between the two U-shaped clamps is provided with several central clamping screws. Both grooves are provided with inner arc plates located below both ends of the cylinder. The upper side of the inner arc plate is a convex arc surface. The inner arc plate below the longitudinal seam and the U-shaped clamps are provided with connected longitudinal through grooves.

2. The fixture for fixing longitudinal seam welding of a cylinder as described in claim 1, characterized in that: The inner arc plate has limiting baffles that cooperate with the U-shaped clamps fixed on both sides in the width direction.

3. The longitudinal seam welding fixture for a cylinder as described in claim 1 or 2, characterized in that: The bottom of the grooves of the two U-shaped clamps and the outer ends of the pressure plate and the inner arc plate are all provided with matching rounded corners.

Images