Back gas protection device for butt joint of small-caliber long pipes

Abstract

The utility model discloses a small-caliber long pipe butt joint back gas protection device which comprises a device body, the device body is of a cylindrical cavity structure, the outer wall of the device body is in a step shape, the device body can be divided into a first-stage step, a second-stage step and a third-stage step according to the outer diameter from large to small, and multiple circles of through holes communicated with the interior of the device body are distributed in the second-stage step in the circumferential direction. The second step of the device body is sleeved with a dispersion device, the dispersion device completely covers multiple circles of through holes in the device body, the third step of the device body is sleeved with an air bag, a center pipe is fixedly installed on the inner side of the device body, a gap is reserved between the center pipe and the inner diameter of the device body, and the two ends of the center pipe protrude out of the device body. The front portion of the center pipe is located in the air bag, the tail of the center pipe is connected with an air pipe, a plurality of supporting frames are fixedly installed on the tail of the device body along the circumference, and pulleys are installed at the tail ends of the supporting frames. According to the utility model, the back gas protection problem during the butt welding of the small-caliber long pipe is solved, the cost is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of welding technology, and in particular to a gas protection device for the back of a small-diameter long pipe joint. Background Technology

[0002] Pipe-to-pipe butt welding is a common structural form widely used in products such as boilers and pressure pipelines. It involves various materials such as non-alloy steel, alloy steel, and stainless steel. For some special materials, such as 91 stainless steel, in order to obtain better weld quality and weld formation during the welding process, it is necessary to protect the back of the weld with a protective gas. For small-diameter and long workpieces that require back gas protection for pipe-to-pipe butt welds, the commonly used technical solution in actual production is to assemble the two workpieces and fix them with a clamp, seal one end of one pipe with a perforated cap or other tool, and introduce protective gas into the end of the other pipe. After the protective gas fills the inside of the pipe, it escapes from the weld joint, and then the subsequent welding work is carried out.

[0003] The advantage of this method is that it is convenient and does not require additional equipment, but its disadvantages are also significant. First, the uniformity of the gas protection formed is poor, and it is difficult to adjust the flow rate of the protective gas, which relies heavily on the experience of the operators. Second, it requires waiting for the protective gas to fill the inside of the workpiece and achieve the protective effect, which reduces production efficiency. Third, when the length of the workpiece tube is very long, a large amount of protective gas, such as argon, is required, which will increase the manufacturing cost accordingly. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model designs a back gas protection device for small-diameter long pipe joint welding, which is used to solve the problem of back gas protection during pipe-to-pipe welding of small-diameter long pipes.

[0005] The present invention adopts the following technical solution:

[0006] A small-diameter long-tube back-mounted gas protection device includes a device body, which is a cylindrical cavity structure with a stepped outer wall. The steps are divided into three levels, from largest to smallest outer diameter: a first level, a second level, and a third level. The second level has multiple rings of through holes circumferentially distributed throughout the device body. A diffusion device is fitted onto the second level of the device body, completely covering the multiple rings of through holes. An air bladder is fitted onto the third level of the device body. A central tube is fixedly installed inside the device body, with a gap between the central tube and the inner diameter of the device body. Both ends of the central tube protrude from the device body. The front of the central tube is located inside the air bladder, and the tail of the central tube is connected to an air tube. Multiple support frames are fixedly installed circumferentially at the tail of the device body, with pulleys installed at the ends of the support frames.

[0007] Preferably, the sum of the cross-sectional areas of the through holes is less than the cross-sectional area of ​​the inner diameter of the central tube.

[0008] Preferably, the surface of the third step is textured with teeth to increase surface roughness.

[0009] Preferably, the airbag is secured to the third step of the device body using a clamp.

[0010] Preferably, the end of the third step is provided with a boss, and the boss is provided with a notch in the circumferential direction.

[0011] Preferably, a circumferential groove is provided on the third step near the position of the second step, and a retaining ring is installed on the circumferential groove.

[0012] Preferably, one side of the diffusion device is attached to the first-stage stepped sidewall of the device body, and the other side is fixed by a retaining ring.

[0013] Preferably, the retaining ring is an open ring.

[0014] Preferably, the airbag has elastic spokes distributed on it.

[0015] Preferably, the support frame is a flexible metal frame, and the air tube is fixedly connected to the tail of the central tube by a clamp.

[0016] The beneficial effects of this utility model are: (1) This utility model solves the problem of back gas protection when welding small-diameter long pipes together and provides a better back gas protection atmosphere; (2) This utility model can effectively reduce the amount of protective gas used in the welding process and reduce manufacturing costs; (3) This utility model is easy to operate, shortens the preparation time before welding the workpiece, and improves production efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model;

[0018] Figure 2 This is a side view diagram of an airbag according to the present invention.

[0019] In the diagram: 1. Device body, 2. Central tube, 3. Dispersion device, 4. Clamping ring, 5. Clamping clamp, 6. Airbag, 61. Spoke, 7. Support frame, 71. Pulley, 8. Air pipe, P. Workpiece tube, I. No air supply, II. Air supply. Detailed Implementation

[0020] The technical solution of this utility model will be further described in detail below through specific embodiments and with reference to the accompanying drawings:

[0021] Example: Figure 1 and Figure 2 As shown, a small-diameter long-tube back-mounted gas protection device includes a device body 1, a central tube 2, a diffusion device 3, a retaining ring 4, a clamp 5, an airbag 6, spokes 61, a support frame 7, a pulley 71, and an air pipe 8. The device body is a cylindrical cavity structure with a stepped outer wall. According to the outer diameter from largest to smallest, it can be divided into a first-level step, a second-level step, and a third-level step. The second-level step has multiple rings of small through holes circumferentially distributed, connecting to the interior of the device body. The sum of the cross-sectional areas of all through holes is smaller than the inner diameter cross-sectional area of ​​the central tube 2. The third-level step has serrated surfaces to increase surface roughness. A circumferential groove is provided on the third-level step near the second level, the width of which is approximately the same as the retaining ring 4. A slightly raised boss is provided at the end of the third-level step, with a notch circumferentially provided on the boss.

[0022] The central tube 2 is fixed to the center of the device body 1 by welding, ensuring the sealing of the connection. The outer diameter of the central tube 2 is smaller than the inner diameter of the device body 1, maintaining sufficient clearance. In the length direction, both ends of the central tube 2 protrude from the device body 1. The diffusion device 3 is assembled on the outer wall of the device body 1, with one side fitting against the first-level stepped sidewall of the device body 1, and the diffusion device 3 completely covering the through hole on the device body. The other side of the diffusion device 3 is fixed by a retaining ring 4, which is an open ring installed in the circumferential groove of the third-level stepped part of the device body 1. The airbag 6 has elastic spokes 61 distributed on it to support it, keeping it relatively slender in the non-inflated state I. The airbag 6 is fitted onto the third-level stepped part of the device body 1 and secured with clamps 5. The support frame 7 is made of flexible metal. One end is fixed to the tail of the device body 1 by bolts, and the other end has an arc that contacts the inner wall of the workpiece P. Multiple support frames 7 are distributed circumferentially at the tail of the device body 1, providing circumferential support for the device. The pulley 71 is installed at the end of the support frame 7. The air pipe 8 is connected to the tail of the central pipe 2 and secured with a clamp.

[0023] Instructions for using this device:

[0024] Before using the device, such as Figure 1As shown, the device body 1 and the central tube 2 are welded together as a whole. A dispersion device 3 of appropriate size is selected based on the inner diameter of the workpiece P. The dispersion device 3 is then installed from the smaller side of the device body 1, with its side flush against the side of the first step of the device body 1. The other side of the dispersion device 3 is flush with the side of the second step of the device body 1. The notch of the opening retaining ring 4 is inserted through the notch of the boss at the end of the third step of the device body 1 and placed within the circumferential groove of the third step, thus fixing the dispersion device 3. An airbag 6 of appropriate size is selected based on the inner diameter of the workpiece P and fitted onto the third step of the device body 1, secured with clamps 5. Elastic spokes 61 are distributed on the airbag 6 to support it, maintaining a relatively slender shape when not inflated (I). Select a suitable support frame 7 based on the inner diameter of workpiece P. This support frame is made of elastic metal, with one end bolted to the tail of the device body 1 and the other end having an arc that contacts the inner wall of workpiece P. Multiple support frames 7 are circumferentially distributed at the tail of the device body 1. Connect the air pipe 8 to the tail of the central pipe 2 and secure it with a clamp. When using this device, insert the air bladder end into the open end of workpiece P. When the pulley 71 contacts the inner wall of workpiece P, because the outer dimensions of the support frame 7 are slightly larger than the inner diameter of workpiece P, the support frame 7 undergoes elastic deformation and applies a certain pressure to the inner wall of workpiece P. The support device body is essentially positioned at the center of workpiece P. By pushing the air pipe 8, the device can be inserted deeper into workpiece P. The pulley 71 rolls on the inner wall of workpiece P, reducing friction. The air bladder 6, under the action of the spokes 61, is in a long, narrow shape, making it easier to push the device into workpiece P. When the device is pushed to the predetermined position... After placement, a suitable flow rate of protective gas is introduced into the air pipe 8. At this time, the protective gas enters the air bag 6 through the central pipe 2. The flow rate of gas flowing in from the air pipe 8 is greater than the flow rate of gas flowing out from the through hole of the device body 1, forming a pressure difference. This causes the air bag to expand and adhere to the inner wall of the workpiece P, which is in the ventilation state II. This prevents the protective gas from escaping from the direction of the air bag 6 and also supports the device, so that the device is basically in the center position of the workpiece P. Subsequently, the gas flows out from the through hole on the device body 1 to the diffusion device 3, and after the gas is homogenized in the diffusion device 3, it escapes and forms a protective gas atmosphere at the designated position of the workpiece P.

[0025] After the device is used, the protective gas supply in the air pipe 8 is turned off. The air bag 6 shrinks into a long strip shape under the elastic action of the spokes 61. Then, the device is removed from the workpiece P by pulling the air pipe 8. The pulley 71 reduces the friction with the inner wall of the workpiece P, making it easier to remove. After the device is completely removed, the elastic deformation of the support frame 7 ends and returns to its initial state.

[0026] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A small-diameter long-tube back-end gas protection device, comprising a device body, characterized in that, The device body is a cylindrical cavity structure with a stepped outer wall. The steps, arranged from largest to smallest outer diameter, are divided into three levels: a first level, a second level, and a third level. The second level has multiple rings of through holes circumferentially distributed throughout the device body. A diffusion device is fitted onto the second level of the device body, completely covering the multiple rings of through holes. An air bladder is fitted onto the third level of the device body. A central tube is fixedly installed inside the device body, with a gap between the central tube and the inner diameter of the device body. Both ends of the central tube protrude from the device body. The front of the central tube is located inside the air bladder, and the tail of the central tube is connected to an air tube. Multiple support frames are fixedly installed circumferentially at the tail of the device body, with pulleys installed at the ends of the support frames.

2. The small-diameter long pipe docking back gas protection device according to claim 1, characterized in that, The sum of the cross-sectional areas of all through holes is less than the cross-sectional area of ​​the inner diameter of the central tube.

3. The small-diameter long pipe docking back gas protection device according to claim 1, characterized in that, The surface of the third step is machined with serrations.

4. The small-diameter long pipe docking back gas protection device according to claim 1, characterized in that, The airbag is secured to the third step of the device body using clamps.

5. The small-diameter long pipe docking back gas protection device according to claim 1, characterized in that, The end of the third step is provided with a boss, and the boss has a notch in the circumferential direction.

6. The small-diameter long pipe docking back gas protection device according to claim 1, characterized in that, A circumferential groove is provided on the third step near the second step, and a retaining ring is installed on the circumferential groove.

7. A small-diameter long-tube docking back gas protection device according to claim 6, characterized in that, One side of the diffusion device is attached to the first-level stepped sidewall of the device body, and the other side is fixed by a retaining ring.

8. A small-diameter long pipe docking back gas protection device according to claim 6, characterized in that, The retaining ring is an open ring.

9. A small-diameter long pipe docking back gas protection device according to claim 1, characterized in that, The airbag has elastic spokes distributed on it.

10. A small-diameter long pipe docking back gas protection device according to claim 1, characterized in that, The support frame is a flexible metal frame, and the air tube is fixedly connected to the tail of the central tube by a clamp.

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