Corrugated pipe air tightness detection device

Abstract

The utility model belongs to the technical field of airtightness detection, and particularly relates to a bellows airtightness detection device. The device comprises a main body, a detection air valve mechanism, a piston mechanism, a piston air valve mechanism, a guide rod and an airtight plug, a through cavity is formed in the main body, and the detection air valve mechanism seals one side of the main body and enables the first air pressure source to introduce detection air into the corrugated pipe; the piston mechanism is arranged in the cavity in an axial sliding manner, and one end, far away from the detection air valve mechanism, of the piston mechanism seals and penetrates through the other side of the cavity; the piston air valve mechanism controls the second air pressure source to drive the piston mechanism to reciprocate. The guide rod penetrates through the piston mechanism, one end is communicated with the detection gas valve mechanism, and the other end is provided with an abutting end face and a gas channel; the airtight plug is arranged at the other end of the main body, is located between the guide rod and the piston mechanism, can be pushed by the piston mechanism to radially expand to be in sealing fit with the inner wall of the corrugated pipe, and recovers when moving reversely, thereby realizing efficient airtight detection.

Description

Technical Field

[0001] This utility model belongs to the field of airtightness testing technology, and in particular relates to a corrugated pipe airtightness testing device. Background Technology

[0002] Corrugated pipes, due to their advantages such as high flexibility, high pressure resistance, and corrosion resistance, are widely used in gas transmission and distribution, household appliance drainage, automotive exhaust, and precision instruments. Their sealing integrity directly affects the safety and reliability of the system: once a hole or pinhole appears, the internal fluid will leak under pressure, not only weakening the pipe's strength and accelerating fatigue, but also potentially leading to media loss, equipment failure, and even major hazards such as fire and electric shock. Therefore, conducting rapid and reliable airtightness testing on finished corrugated pipes before they leave the factory or are assembled has become a core aspect of quality control in the industry.

[0003] Currently, common testing methods often employ a split fixture consisting of an external plug and either air blowing or vacuuming. The testing personnel must first select a rubber or metal plug of the corresponding size, insert it into the tube end, and then connect it to an external air circuit. During pressurization, leaks are detected using soapy water, pressure drop, or acoustic sensors. While these devices are simple in principle, they suffer from drawbacks such as a wide variety of plug sizes, time-consuming assembly, and inconsistent sealing due to reliance on manual tightening. Furthermore, the gas passage requires an additional flexible hose and external valve control, resulting in complex piping and a high risk of dead-end leaks. For continuous testing on mass production lines, this approach is not only inefficient but also prone to problems such as plug displacement, pressure fluctuations, and misinterpretations of test results.

[0004] Especially when the inner diameter tolerance of the bellows is large or the inner wall is contaminated with oil, existing plugs cannot form a stable and uniform radial seal in a short time. The mechanism driving the plug expansion is separate from the detection air path, resulting in long pipelines, numerous connection points, and a high probability of leakage. The piston or clamping element lacks guiding and limiting functions, making it prone to eccentric wear under pressure, leading to insufficient plug expansion or uneven stress. Furthermore, the mixing of the detection and driving air paths makes it difficult to monitor pressure changes in both paths in real time and to quickly depressurize, posing a safety hazard. In summary, there is an urgent need for a bellows airtightness testing device with a compact structure, controllable plug expansion, integrated detection air path, and easy and quick clamping to solve the technical problems of poor sealing reliability, low operating efficiency, and insufficient safety. Utility Model Content

[0005] The purpose of this invention is to address the above-mentioned shortcomings and provide a device for testing the airtightness of bellows.

[0006] A bellows airtightness testing device, comprising:

[0007] The main body has a through cavity along its length.

[0008] A detection valve mechanism is located at one end of the main body and airtightly seals one side of the through cavity, and is used to connect to a first air pressure source to introduce detection gas into the bellows to be tested.

[0009] A piston mechanism is slidably disposed in the through cavity in the axial direction, with one end of it away from the detection valve mechanism sealing the other side of the through cavity;

[0010] A piston valve mechanism is connected to the main body and airtightly communicates with the through cavity, and is used to connect to and control a second air pressure source to drive the piston mechanism to slide axially within the through cavity.

[0011] A guide rod passes through the piston mechanism along the axial direction. One end is in airtight communication with the detection valve mechanism, and the other end extends to the outside of the through cavity and is provided with an abutting end face. The guide rod has a gas channel along its length to introduce the detection gas into the bellows to be tested.

[0012] An airtight plug is disposed at the other end of the main body, with one end abutting against the abutting end face and the other end abutting against the piston mechanism. The airtight plug can expand radially to abut against the inner wall of the bellows to be tested to form an airtight seal.

[0013] The piston mechanism moves axially and approaches the airtight plug, causing the airtight plug to expand radially to abut against the inner wall of the bellows under test for an airtight seal; when the piston mechanism moves axially and moves away from the airtight plug, the airtight plug returns to its initial state and releases the airtight seal with the bellows under test.

[0014] Furthermore, the piston mechanism includes a piston rod and a piston head fixedly connected to one end of the piston rod. The other end of the piston rod is provided with an abutting convex surface that abuts against the airtight plug. The piston head can slide axially within the through cavity, and its outer edge is provided with a sealing ring to reduce gas leakage and enable the piston mechanism to move axially when driven by the second air pressure source.

[0015] Furthermore, the piston valve mechanism includes a piston valve component and a valve adjusting component, wherein the piston valve component is in airtight communication with the through cavity and is used to connect or disconnect the second air pressure source; the valve adjusting component is in airtight connection with the piston valve component and is used to adjust the opening degree of the piston valve component to control the driving force applied by the second air pressure source to the piston mechanism, thereby realizing the axial sliding of the piston mechanism.

[0016] Furthermore, the airtight plug is made of an elastic material and has at least one annular rib on its outer circumference, which is used to expand radially and fit tightly against the inner wall of the bellows under test when subjected to axial compression, so as to achieve a reliable airtight seal.

[0017] Furthermore, the abutting end face of the guide rod is provided with a stop protrusion, which abuts against the airtight plug to restrict the axial movement of the airtight plug.

[0018] Furthermore, a pressure relief valve is provided at the end of the main body away from the airtight plug, which is used to quickly release the remaining gas in the through cavity or gas channel when the test is completed or an abnormality occurs.

[0019] Furthermore, the detection valve mechanism and / or the piston valve mechanism are equipped with pressure sensors for monitoring pressure changes of the first pressure source and / or the second pressure source.

[0020] Furthermore, a detachable fixing structure is provided between the main body and the corrugated pipe to be tested, which is used to securely connect the two during the testing process to prevent loosening under high pressure.

[0021] The beneficial effects of this utility model are:

[0022] This invention provides a bellows airtightness testing device. The device compactly integrates the testing valve mechanism, piston mechanism, guide rod, and airtight plug into one unit, eliminating the problems of redundant external piping and numerous connection interfaces in traditional devices, making the testing process more efficient and convenient. The through-cavity allows the piston mechanism to move smoothly along the axial direction, ensuring uniform force on the airtight plug and preventing airtightness testing failures due to eccentricity or tilting. The guide rod passes through the piston mechanism and has a built-in gas channel, serving both to guide and limit the piston's movement and to directly deliver the testing gas to the bellows under test, significantly reducing pipeline length and the number of connection points, greatly reducing the risk of system leakage, and improving testing accuracy. Under axial compression, the airtight plug can expand radially and uniformly, tightly fitting the inner wall of the bellows, adapting to bellows of different specifications and tolerances, further enhancing testing reliability. Furthermore, when the piston mechanism removes the axial force, the plug automatically returns to its initial state, greatly simplifying the loading and unloading process and effectively improving the efficiency, safety, and ease of operation of the testing device. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a bellows airtightness testing device.

[0024] Figure 2 A cross-sectional view (AA) of the structure of the bellows airtightness testing device;

[0025] Figure 3 This is a schematic diagram of the assembly of a bellows airtightness testing device.

[0026] Reference numerals: 1. Air tightness testing device; 10. Main body; 101. Through cavity; 20. Testing valve mechanism; 30. Piston mechanism; 301. Piston rod; 302. Piston head; 303. Abutting convex surface; 40. Piston valve mechanism; 401. Piston valve component; 402. Valve adjusting component; 50. Guide rod; 501. Abutting end face; 502. Stopping convex surface; 503. Gas passage; 60. Air tightness plug. Detailed Implementation

[0027] The following detailed description, in conjunction with embodiments, provides a further specific account of the bellows airtightness testing device of this utility model. For the sake of simplicity, this document cannot exhaustively list all alternative technical features and implementation schemes included in this utility model. Therefore, those skilled in the art should understand that any technical feature and implementation scheme within this embodiment does not limit the scope of protection of this utility model, which includes all alternative technical features and implementation schemes adopted by those skilled in the art without inventive effort. Specifically, any implementation scheme obtained by replacing any technical feature in this utility model or combining any two or more technical features provided by this utility model should be within the scope of protection of this utility model.

[0028] This embodiment provides a bellows airtightness testing device 1, such as... Figures 1-3 The airtightness testing device 1, as described above, includes:

[0029] The main body 10 has a through cavity 101 along its length;

[0030] The detection valve mechanism 20 is located at one end of the main body 10 and is airtight on one side of the through cavity 101. It is used to connect to the first air pressure source to introduce detection gas into the bellows to be tested.

[0031] The piston mechanism 30 is slidably disposed in the through cavity 101 in the axial direction, and its end away from the detection valve mechanism 20 closes the other side of the through cavity 101.

[0032] The piston valve mechanism 40 is connected to the main body 10 and airtightly communicates with the through cavity 101. It is used to connect to the second air pressure source to drive the piston mechanism 30 to slide axially within the through cavity 101.

[0033] The guide rod 50 passes through the piston mechanism 30 along the axial direction. One end is in airtight communication with the detection valve mechanism 20, and the other end extends to the outside of the through cavity 101 and is provided with an abutting end face 501. The guide rod 50 has a gas channel 503 along its length direction for introducing the detection gas into the bellows to be tested.

[0034] An airtight plug 60 is disposed at the other end of the main body 10. One end abuts against the abutting end face 501, and the other end abuts against the piston mechanism 30. The airtight plug 60 can expand radially to abut against the inner wall of the bellows to be tested to form an airtight seal.

[0035] When the piston mechanism 30 moves axially and approaches the airtight plug 60, it causes the airtight plug 60 to expand radially to abut against the inner wall of the bellows under test for airtight sealing. When the piston mechanism 30 moves axially and moves away from the airtight plug 60, the airtight plug 60 returns to its initial state and releases the airtight seal with the bellows under test.

[0036] In a typical embodiment, the main body 10 is made of metal tubing or hard alloy material, with a through cavity 101 machined along its length. The detection valve mechanism 20 can be a conventional valve unit with a connector, installed at one end of the main body 10 to achieve an airtight seal on one side of the through cavity 101. The piston mechanism 30 can slide axially within the through cavity 101; the end of the piston mechanism 30 away from the detection valve mechanism 20 seals the other side of the through cavity 101. The piston valve mechanism 40 is connected to the main body and airtightly communicates with the through cavity 101, used to connect to a second air pressure source, pushing or pulling the piston mechanism 30 by filling / draining gas into the through cavity 101. A guide rod 50 passes axially through the piston mechanism 30 along the main body 10, with one end airtightly communicating with the end of the detection valve mechanism 20, and the other end extending to the outside of the through cavity 101 and machined with an abutment face 501. The guide rod 50 has a longitudinally penetrating gas channel 503 inside, used to introduce detection gas from the detection gas valve mechanism 20 into the bellows under test for airtightness testing. One end of the airtight plug 60 abuts against the contact surface 501 of the guide rod 50, and the other end abuts against the piston mechanism 30. The piston mechanism 30 moves axially towards and squeezes the airtight plug 60, causing it to expand radially and form an airtight seal against the inner wall of the bellows under test; sliding in the opposite direction away from the airtight plug 60 causes it to spring back to its initial state, releasing the airtight seal with the bellows under test.

[0037] In some embodiments, the piston mechanism 30 includes a piston rod 301 and a piston head 302 fixedly connected to one end of the piston rod 301. The other end of the piston rod 301 is provided with an abutting convex surface 303 and abuts against the airtight plug 60. The piston head 302 can slide in the axial direction within the through cavity 101, and its outer edge is provided with a sealing ring to reduce gas leakage and enable the piston mechanism 30 to move axially when driven by the second air pressure source.

[0038] In an optional embodiment, the piston head 302 of the piston mechanism 30 is made of metal or composite material, and a wear-resistant and high-temperature resistant sealing ring is installed on its outer periphery. The piston rod 301 can be an integral structure coaxially connected to the piston head 302, or it can be disassembled and assembled by means of threads or pins. The end of the piston rod 301 is machined with an abutting convex surface 303 for abutting against the airtight plug 60.

[0039] In some embodiments, the piston valve mechanism 40 includes a piston valve component 401 and a valve adjusting component 402. The piston valve component 401 is in airtight communication with the through cavity 101 and is used to connect or disconnect the second air pressure source. The valve adjusting component 402 is in airtight connection with the piston valve component 401 and is used to adjust the opening degree of the piston valve component 401 to control the driving force applied by the second air pressure source to the piston mechanism 30, thereby realizing the axial sliding of the piston mechanism 30.

[0040] In one feasible implementation, the piston valve mechanism 40 is located on the side or end of the main body 10. The piston valve component 401 can be connected to the main body 10 by thread or snap-fit ​​and is airtightly connected to the through cavity 101. An internal sealing assembly ensures airtightness under high-pressure conditions. When testing the bellows under test, the piston valve component 401 is connected to a second air pressure source, the valve regulating component 402 is opened, and gas is introduced into the through cavity 101. The piston mechanism 30 is pushed and slides axially, approaching the airtight plug 60, causing it to expand radially and abut against the inner wall of the bellows under test to form an airtight seal. After the airtightness test of the bellows under test is completed, the valve regulating component 402 is closed, and the gas inside the through cavity 101 is discharged. The airtight plug returns to its initial state, causing the piston mechanism 30 to reset. During this process, the valve regulating component 402 can be equipped with a pressure gauge or sensor to dynamically monitor and fine-tune the opening of the valve regulating component 402, thereby ensuring the sealing effect while preventing excessive pressure from causing structural deformation or safety risks.

[0041] In some embodiments, the airtight plug 60 is made of an elastic material and has at least one annular rib on its outer circumferential surface, which is used to expand radially when subjected to axial compression and fit tightly against the inner wall of the bellows to be tested, so as to achieve a reliable airtight seal.

[0042] In optional embodiments, the airtight plug 60 is preferably made of a material with high elastic recovery force, such as silicone rubber, fluororubber, or polyurethane, and its outer circumferential surface is machined or pre-fabricated with one or more annular ribs. After being axially compressed by the piston mechanism 30, these ribs expand radially along with the plug and form segmented contact with the inner wall of the bellows. If the inner wall of the bellows has a certain tolerance or roughness, the annular ribs can effectively fill the gaps, increase the contact area, and thus ensure that internal gas is not easily leaked.

[0043] In some embodiments, the abutting end face 501 of the guide rod 50 is provided with a stop protrusion 502, which abuts against the airtight plug 60 to restrict the axial movement of the airtight plug 60.

[0044] In some optional embodiments, a stop protrusion 502 may be machined on the abutment end face 501 of the guide rod 50. When the airtight plug 60 is compressed by the piston mechanism 30, the airtight plug 60 will move slightly in the axial direction and begin to expand radially. The stop protrusion 502 can be designed according to the thickness, diameter, and other dimensions of the plug to ensure that the radial expansion of the plug is just right and that excessive compression will not cause material damage or uneven deformation.

[0045] In some embodiments, a pressure relief valve is provided at the end of the main body 10 away from the airtight plug 60, for quickly releasing the remaining gas in the cavity 101 or gas passage 503 when the detection is completed or an abnormality occurs.

[0046] In some optional embodiments, one or more pressure relief valves are provided at the end of the main body 10 away from the airtight plug 60. These valves can be common safety valves, needle valves, or quick-release valves. The pressure relief valve is connected to the through cavity 101 or the gas pipeline 503. When the detection is completed or an abnormal pressure occurs, the valve can be opened manually or automatically to quickly release the internal gas and prevent excessive pressure from damaging the device.

[0047] In some embodiments, the detection valve mechanism 20 and / or piston valve mechanism 40 are provided with pressure sensors for monitoring pressure changes of the first pressure source and / or the second pressure source.

[0048] In some optional embodiments, one or more pressure sensors may be installed on the detection valve mechanism 20 and / or the piston valve mechanism 40, respectively, and the measured pressure values ​​may be output through a display instrument or a data transmission module. For example, a pressure sensor may be installed at the detection valve mechanism 20 to monitor the pressure changes inside the gas pipeline 503 in real time; another sensor may also be installed at the piston valve mechanism 40 to monitor the driving pressure. In an automated detection system, the sensor signals may also be linked with the control system to achieve automatic judgment and alarm.

[0049] In some embodiments, a detachable fixing structure is provided between the main body 10 and the bellows to be tested, which is used to securely connect the two during the testing process to prevent loosening under high pressure.

[0050] In some optional embodiments, a detachable fixing structure is arranged at the connection between the main body 10 and the bellows, which can be a clamp, quick-connect coupling, flange, or other mechanical connector. For example, a clamp-type quick-connect coupling can be used for small-diameter bellows to facilitate frequent assembly and disassembly; a flange bolt connection can be used for large-diameter or high-pressure applications. This fixing structure provides a stable connection during testing, preventing the bellows from slipping or vibrating under high pressure.

[0051] The working principle of the bellows airtightness testing device provided by this utility model is as follows:

[0052] Before the actual testing begins, the open end of the bellows to be tested is first inserted and fixed to the side of the main body 10 away from the airtight plug 60. The other end of the bellows to be tested is sealed. The main body 10 is secured by a detachable fixing structure after the bolts are pre-tightened or the clamps are locked, ensuring that the bellows to be tested is coaxial with the main body 10 and does not shift under high pressure. At the same time, the testing air valve mechanism 20 is connected to the first air pressure source but kept closed to prevent premature inflation. Subsequently, the second air pressure source is connected to the through cavity 101 through the piston air valve mechanism 40. The air valve adjustment component 402 is slightly opened, allowing the driving gas to enter the rear cavity of the piston mechanism 30 in the through cavity 101. The gas pressure overcomes the frictional resistance between the piston head 302 and the inner wall of the through cavity 101, pushing the piston rod 301 smoothly forward toward the airtight plug 60. The guide rod 50 provides coaxial constraint during this process, preventing the piston mechanism 30 from wobbling, and the axial force is accurately transmitted to the end face of the airtight plug 60.

[0053] As the piston mechanism 30 continues to move forward and fully contacts the airtight plug 60, the airtight plug 60 begins to expand radially under axial compression. Its outer circumferential annular ribs expand towards the inner wall of the bellows, forming multi-ring segmented contact. The stop convex surface 502 at the end face of the guide rod 50 restricts further axial displacement of the airtight plug 60, so that almost all the subsequent air pressure energy applied by the piston mechanism 30 is converted into radial deformation of the airtight plug 60, thereby forming a uniform and reliable circumferential seal on the inner wall of the bellows under test. At this time, the piston valve component 401 is adjusted to maintain a constant driving chamber pressure, and the piston mechanism 30 stops at the set position.

[0054] After sealing is completed, the detection valve mechanism 20 is opened, and the detection gas from the first pressure source flows directly into the cavity of the bellows under test through the gas channel 503 inside the guide rod 50. Since the airtight plug 60 has sealed the pipe end, the detection gas can only fill the bellows body and its pressure is limited by its structural integrity. A pressure sensor installed near the detection valve mechanism 20 provides real-time feedback on the internal pressure of the bellows: if the bellows has micropores or cracks, the pressure will drop in a short time, and the bellows under test will be recorded as failing the airtightness test; if the pressure remains within the set range, the bellows under test will be recorded as passing the airtightness test. Throughout the entire inflation and pressure holding phase, the driving pressure of the piston mechanism 30 remains constant to prevent misjudgment caused by loosening of the airtight plug 60.

[0055] After the test, first close the test air valve mechanism 20 and open the pressure relief valve. The residual gas in the bellows is quickly discharged through the pressure relief passage, eliminating potential impact on personnel and equipment. Then, slowly rotate the air valve adjusting component 402 to the closed position. The gas in the piston rear chamber is released through the piston air valve component 401. Under the elastic recovery of the airtight plug 60 and the action of residual gas pressure, the piston mechanism 30 slides in the opposite direction and gradually moves away from the plug. After the airtight plug 60 loses axial compression, it recovers its original shape through its own elasticity, and the annular rib retracts and detaches from the inner wall of the bellows, releasing the seal. At this time, the fixing structure is loosened, the bellows can be safely removed, the device returns to its initial state, and the next round of testing can begin.

[0056] For those skilled in the art, other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, but obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this invention.

Claims

1. A device for detecting the gas tightness of a bellows, characterized in that, The utility model relates to a kind of detection device for corrugated pipe, including: Main body, along its length direction, through cavity is opened; Detection gas valve mechanism, is arranged in one end of the main body and airtightly closed one side of the through cavity, for connecting first air pressure source to guide detection gas into the inside of the corrugated pipe to be measured; Piston mechanism, it is slidably arranged in the through cavity along axial direction, its one end away from the detection gas valve mechanism closes the other side of the through cavity; Piston gas valve mechanism, with the main body is connected and is airtight with the through cavity Communication, for connecting and control second air pressure source to drive piston mechanism axial sliding in the through cavity; Guide rod, along axial direction, through the piston mechanism, one end airtight with the detection gas valve mechanism, the other end extends to the outside of the through cavity and is provided with abutting end face, the guide rod is opened along its length direction, gas passage is used for guiding detection gas into the corrugated pipe to be measured; Airtight plug, it is arranged in the other end of the main body, one end is abutted with the abutting end face, the other end is abutted with the piston mechanism, the airtight plug can be radially expanded to abut with the inner wall of the corrugated pipe to be measured and form airtight seal; Wherein, the piston mechanism is moved along axial direction and is close to the airtight plug, promote the airtight plug radially expanded to abut with the inner wall of the corrugated pipe to be measured and form airtight seal;When the piston mechanism is moved along axial direction and is away from the airtight plug, the airtight plug restores to initial state and removes airtight seal with the corrugated pipe to be measured.

2. The bellows air tightness testing device of claim 1, wherein, The piston mechanism includes piston rod and piston head fixedly connected with one end of the piston rod, the other end of the piston rod is provided with abutting convex surface and is abutted with the airtight plug;The piston head can slide in the through cavity along axial direction, and its outer edge is provided with sealing ring, for reducing gas leakage when the second air pressure source drives and making the piston mechanism axial movement.

3. The bellows air tightness testing device of claim 1, wherein, The piston gas valve mechanism includes piston valve and valve adjusting part, wherein, the piston valve is airtight with the through cavity and is used to connect or cut off the second air pressure source;The valve adjusting part is airtight with the piston valve, for adjusting the opening degree of the piston valve, to control the driving force exerted on the piston mechanism by the second air pressure source, so as to realize the axial sliding of piston mechanism.

4. The bellows air tightness testing device of claim 1, wherein, The airtight plug is made of elastic material, and at least one annular rib is arranged on the outer circumferential surface of the airtight plug, which is used to radially expand and tightly fit with the inner wall of the corrugated pipe to be measured when subjected to axial extrusion, so as to realize reliable airtight seal.

5. The bellows air tightness testing device of claim 1, wherein, The abutting end face of the guide rod is provided with a stop convex surface, which is abutted with the airtight plug, for limiting the axial movement of the airtight plug.

6. The bellows air tightness testing device of claim 1, wherein, The one end of the main body away from the airtight plug is provided with a pressure relief valve, which is used to quickly discharge the remaining gas in the through cavity or gas passage when detection is completed or abnormality occurs.

7. The bellows air tightness testing device of claim 1, wherein, Pressure sensor is arranged on the detection gas valve mechanism and / or the piston gas valve mechanism, which is used to monitor the pressure change of the first air pressure source and / or the second air pressure source.

8. The bellows air tightness testing apparatus according to any one of claims 1 to 7, characterized by, Detachable fixing structure is arranged between the main body and the corrugated pipe to be measured, which is used to stably connect the two during detection, so as to prevent loosening under high pressure condition.

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