Pipeline airtightness detection equipment

Abstract

The present invention discloses a pipeline airtightness detection device, which includes a frame, several differential pressure detection combined isolating valves, and several air pressure difference detection sensors. A standard pipeline corresponding to each pipeline to be detected is fixed on the frame; several pairs of pipeline end sealing connection devices are installed on the frame. Each pipeline end sealing unit is used for sealing connection with one end of the pipeline to be detected at the corresponding position. The other pipeline end sealing unit in each pair of pipeline end sealing connection devices is connected to the first air outlet channel in the corresponding differential pressure detection combined isolating valve. The other end of each standard pipeline is connected to the second air outlet channel in the corresponding differential pressure detection combined isolating valve. Two air inlet ends of each air pressure difference detection sensor are respectively connected to the first air outlet channel and the second air outlet channel in the corresponding differential pressure detection combined isolating valve; the present invention can automatically detect the airtightness of the pipeline to be detected.

Description

Technical Field

[0001] The present invention relates to the technical field of airtightness detection equipment, and particularly relates to a pipeline airtightness detection equipment. Background Art

[0002] After the pipeline is produced, it is necessary to detect the airtightness of the pipeline. The main purpose is to detect whether there is a leakage in the pipeline. At present, the method for detecting the airtightness of the pipeline is as follows: First, one end of the pipeline to be tested and the standard pipeline are both blocked. Then, one of the sealing joints is hermetically connected to the other end of the pipeline to be tested, and the other sealing joint is hermetically connected to the other end of the standard pipeline. Then, one of the above-mentioned sealing joints is connected to the air outlet end of one of the air valves through one connecting pipe, and the other sealing joint is connected to the air outlet end of the other air valve through another connecting pipe. Immediately afterwards, the air inlet ends of the two air valves are both connected to the air inlet pipe. In addition, one of the air inlet ends of the air pressure difference detection sensor needs to be communicated with one of the above-mentioned connecting pipes, and the other air inlet end of the air pressure difference detection sensor needs to be communicated with the other connecting pipe. In addition, the air pressure difference detection sensor needs to be electrically connected to the controller. When the detection starts, the two air valves are opened so that the air inlet pipe fills the compressed air into the pipeline to be tested and the standard pipeline. After the inflation is completed, the two air valves are closed. Then, the air pressure difference detection sensor starts to detect the air pressure difference between one connecting pipe and the other connecting pipe. If the air pressure difference between one connecting pipe and the other connecting pipe is less than the preset value, it means that there is no leakage in the pipeline to be tested. If the air pressure difference between one connecting pipe and the other connecting pipe is greater than the preset value, it means that there is a leakage in the pipeline to be tested, thus realizing the detection of the airtightness of the pipeline to be tested. However, in the above detection process, the inflation and deflation of the pipeline to be tested and the standard pipeline need to be independently controlled through two air valves, resulting in the disadvantages of complex control and complex structure. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a pipeline airtightness detection equipment, which can simultaneously control the inflation and stop inflation of the pipeline to be tested and the standard pipeline, thus having the advantage of simple control, and can simplify the structure of the pipeline airtightness detection equipment.

[0004] The pipeline airtightness detection device of the present invention includes a frame, a plurality of differential pressure detection combined isolation valves, and a plurality of air pressure difference detection sensors. The plurality of differential pressure detection combined isolation valves and the plurality of air pressure difference detection sensors each correspond one-to-one to each pipeline to be detected. A standard pipeline corresponding one-to-one to each pipeline to be detected is fixed on the frame; A plurality of pairs of pipeline end sealing connection devices are installed on the frame. The two pipeline end sealing units in each pair of pipeline end sealing connection devices are respectively installed on the frame at the positions of the two ends of the corresponding pipeline to be detected. Each pipeline end sealing unit is used for sealing connection with one end of the pipeline to be detected at the corresponding position. One of the pipeline end sealing units in each pair of pipeline end sealing connection devices is used for blocking one end of the pipeline to be detected, and the other pipeline end sealing unit in each pair of pipeline end sealing connection devices is connected to the first air outlet channel in the corresponding differential pressure detection combined isolation valve. One end of each standard pipeline is blocked, and the other end of each standard pipeline is connected to the second air outlet channel in the corresponding differential pressure detection combined isolation valve. The two air inlet ends of each air pressure difference detection sensor are respectively connected to the first air outlet channel and the second air outlet channel in the corresponding differential pressure detection combined isolation valve; In the above structure, for the picking and placing of each pipeline to be detected, an independent electromagnet can be used for adsorption. For example, a support frame is installed on the manipulator, and electromagnets corresponding one-to-one to each pipeline to be detected are installed at the bottom of the support frame. When the electromagnet is energized, the electromagnet can magnetically adsorb the pipeline to be detected. When the electromagnet is powered off, the electromagnet can release the pipeline to be detected. In this way, the movement of the pipeline to be detected can be conveniently realized.

[0005] The pipeline airtightness detection device of the present invention, wherein each differential pressure detection combined isolation valve includes a base, a first valve seat, a first cylinder and a first piston; the lower end of the first valve seat is fixed on the base, and a first sealing structure is arranged between the lower end of the first valve seat and the base. A cavity is formed between the first valve seat and the base. The first cylinder is fixed at the upper end of the first valve seat. The first piston is vertically slidably disposed in the first valve seat. The lower end of the first piston extends into the cavity. A second sealing structure is arranged between the first piston and the first valve seat. The upper end of the first piston is connected to the driving end of the first cylinder. An air inlet channel, a first air outlet channel and a second air outlet channel are arranged in the base. One end of the air inlet channel, one end of the first air outlet channel and one end of the second air outlet channel are all communicated with the cavity. The other end of the air inlet channel is used for connecting with an air inlet pipe. The other end of the first air outlet channel is used for sealing connection with another pipe end sealing unit in the corresponding pipe end sealing device for the pipeline. The other end of the second air outlet channel is used for connecting with the other end of the corresponding standard pipeline. A sealing gasket is embedded at the lower end of the first piston. After the first cylinder drives the first piston to move downward, the sealing gasket is used for abutting against the upper end surface of the base and for blocking one end of the first air outlet channel and one end of the second air outlet channel. A first ventilation hole and a second ventilation hole are further arranged on the base. One end of the first ventilation hole and one end of the second ventilation hole are respectively communicated with the first air outlet channel and the second air outlet channel. The other end of the first ventilation hole is used for connecting with one of the air inlet ends in the corresponding differential pressure detection sensor. The other end of the second ventilation hole is used for connecting with the other air inlet end in the corresponding differential pressure detection sensor; by adopting such a differential pressure detection combined isolation valve, it is possible to simultaneously control the inflation and stop of inflation of the pipeline to be measured and the standard pipeline.

[0006] The pipeline airtightness detection device of the present invention, wherein the outer edges of one end of the first air outlet channel and the outer edges of one end of the second air outlet channel both protrude from the upper end surface of the base; after setting the outer edges of one end of the first air outlet channel and the outer edges of one end of the second air outlet channel to protrude from the upper end surface of the base, after the first cylinder drives the first piston to move downward, the outer edges of one end of the first air outlet channel and the outer edges of one end of the second air outlet channel can better squeeze the gasket, so that the gasket can more reliably block one end of the first air outlet channel and one end of the second air outlet channel; the first sealing structure includes a first sealing ring, a circular boss is provided on the lower end surface of the first valve seat, a first circular groove is provided on the upper end surface of the base, the first sealing ring is embedded in the first circular groove, and the circular boss is inserted into the first circular groove and used to press the first sealing ring, and the first sealing ring is in close contact and sealed with both the first circular groove and the circular boss; after adopting this first sealing structure, after the first valve seat is assembled on the base, reliable sealing can be achieved between the lower end of the first valve seat and the base; the second sealing structure includes a plurality of second sealing rings distributed along the axial direction of the first piston, first circular grooves corresponding to each second sealing ring are provided on the outer wall of the first piston, each second sealing ring is embedded in the first circular groove at the corresponding position, and each second sealing ring is in close contact and sealed with the inner wall of the first valve seat and the first circular groove at the corresponding position; after adopting this second sealing structure, reliable sealing can be achieved between the first piston and the first valve seat; a "T"-shaped card slot is provided at the upper end of the first piston, a "T"-shaped card block is provided at the driving end of the first cylinder, and the card block is engaged with the card slot; after adopting this structure, the upper end of the first piston can be reliably connected to the driving end of the first cylinder, and when the driving end of the first cylinder contracts, the first cylinder can drive the first piston to move upward, and when the driving end of the first cylinder extends, the first cylinder can drive the first piston to move downward.

[0007] The pipeline airtightness detection device of the present invention. Among them, the differential pressure detection combined isolating valve further includes a second valve seat, a second air cylinder and a second piston. The lower end of the second valve seat is fixed on the base, the second air cylinder is fixed to the upper end of the second valve seat, the second piston is slidably installed vertically in the second valve seat, the upper end of the second piston is fixed to the driving end of the second air cylinder, and a plug rod with an outer diameter smaller than that of the second piston is provided at the lower end of the second piston. A first sealing ring is sleeved outside the plug rod. A third ventilation hole is provided in the base, and one end of the third ventilation hole is communicated with the first air outlet channel. After the second air cylinder drives the second piston to move downward, the lower end of the plug rod is used to insert into the other end of the third ventilation hole, and the first sealing ring is used to abut against the upper end surface of the base and block the third ventilation hole. An exhaust joint is connected to the side wall of the second valve seat. After the second air cylinder drives the second piston to move upward, the exhaust joint is used to communicate with the third ventilation hole through the second valve seat; by adopting this structure, after the detection of the pipeline to be measured is completed, when the second air cylinder drives the second piston to move upward, the sealing ring can release the blockage of the third ventilation hole. At this time, the compressed air filled in the pipeline to be measured can be discharged in sequence through the first air outlet channel, the third ventilation hole, the second valve seat and the exhaust joint. In this way, when the exhaust joint is connected to one end of the blow pipe and one end of the blow pipe is arranged in the pipeline end chamfering mechanism, the compressed air blown out through the blow pipe can blow out the metal chips in the pipeline end chamfering mechanism, that is, the reuse of the compressed air is realized to achieve the purpose of energy saving; the outer edge of the other end of the third ventilation hole protrudes from the upper end surface of the base; by adopting this structure, after the second air cylinder drives the second piston to move downward, the outer edge of the other end of the third ventilation hole can better squeeze the first sealing ring. In this way, the first sealing ring can better block the third ventilation hole.

[0008] The pipeline airtightness detection device of the present invention. Among them, a fourth ventilation hole is further provided on the base, one end of the fourth ventilation hole is communicated with the first air outlet channel, and the other end of the fourth ventilation hole is used to connect with a pressure gauge; by adopting this structure, the staff can clearly know the real-time air pressure in the first air outlet channel through the pressure gauge.

[0009] When the above differential pressure detection combined partition valve is working, first, the driving end of the second cylinder drives the second piston to move downward so that the first sealing ring seals the third ventilation hole. Then, the driving end of the first cylinder drives the first piston to move upward so that the sealing pad releases the sealing of one end of the first air outlet channel and one end of the second air outlet channel. At this time, the compressed air from the air inlet pipe can enter the cavity through the air inlet channel. The compressed air entering the cavity can be filled into the pipeline to be measured through the first air outlet channel, and the compressed air entering the cavity can be filled into the standard pipeline through the second air outlet channel. After the pipeline to be measured and the standard pipeline are filled with air (generally, a time delay method can be used to ensure that the pipeline to be measured and the standard pipeline are filled with air), the driving end of the first cylinder drives the first piston to move downward so that the sealing pad seals one end of the first air outlet channel and one end of the second air outlet channel. At this time, the air inlet channel, one end of the first air outlet channel, and one end of the second air outlet channel are not connected to each other. Then, the differential pressure detection sensor starts to detect the pressure difference between the first air outlet channel and the second air outlet channel. If the pressure difference between the first air outlet channel and the second air outlet channel is less than the preset value, it means that there is no leakage in the pipeline to be measured (because there must be no leakage in the standard pipeline). If the pressure difference between the first air outlet channel and the second air outlet channel is greater than the preset value, it means that there is a leakage in the pipeline to be measured (because there must be no leakage in the standard pipeline). In this way, the pipeline to be measured is unqualified. Then, during the subsequent operation of the pipeline airtightness detection equipment, the unqualified pipeline can be placed in the unqualified area. After the above detection is completed, the second cylinder can drive the second piston to move upward. When the second piston moves upward, the first sealing ring can release the sealing of the third ventilation hole. At this time, the compressed air filled in the pipeline to be measured can be discharged in sequence through the first air outlet channel, the third ventilation hole, the second valve seat, the exhaust joint, and the blow pipe. In this way, the compressed air blown out through the blow pipe can blow out the metal chips in the pipeline end chamfering mechanism, that is, the compressed air is reused to achieve the purpose of energy saving.

[0010] The pipeline airtightness detection device of the present invention, wherein each pipeline end sealing unit includes a sliding seat and a third cylinder. The sliding seat is slidably connected to the frame through a slide rail assembly. The third cylinder is fixed to the frame, and the sliding seat is fixed to the piston rod of the third cylinder. Each pipeline end sealing unit further includes an outer wrapping type pipeline end sealing joint or an inner expansion type pipeline end sealing joint fixed on the inner end face of the sliding seat. The third cylinder is used to drive the sliding seat to move along the axial direction of the pipeline to be detected so that the outer wrapping type pipeline end sealing joint or the inner expansion type pipeline end sealing joint approaches or moves away from the pipeline to be detected. When the outer wrapping type pipeline end sealing joint or the inner expansion type pipeline end sealing joint approaches the pipeline to be detected, the outer wrapping type pipeline end sealing joint or the inner expansion type pipeline end sealing joint is used for sealing connection with the end of the pipeline to be detected; one of the outer wrapping type pipeline end sealing joints or the inner expansion type pipeline end sealing joints in each pair of pipeline end sealing connection devices is used for blocking one end of the pipeline to be detected, and the other outer wrapping type pipeline end sealing joint or the inner expansion type pipeline end sealing joint in each pair of pipeline end sealing connection devices is connected to the first air outlet channel in the corresponding differential pressure detection combined partition valve; after adopting this structure, when the piston rod of the third cylinder extends, the third cylinder can drive the sliding seat to slide so that the outer wrapping type pipeline end sealing joint or the inner expansion type pipeline end sealing joint installed on the sliding seat is in sealing connection with the end of the pipeline to be detected. When the piston rod of the third cylinder contracts, the third cylinder can drive the sliding seat to slide so that the outer wrapping type pipeline end sealing joint or the inner expansion type pipeline end sealing joint installed on the sliding seat is separated from the pipeline to be detected.

[0011] The pipeline airtightness detection device of the present invention, wherein the outer wrapping type pipeline end sealing joint includes a first connection seat, a first connector, a third piston and a sealing ring group; a sliding cavity is arranged inside one end of the first connection seat, the third piston is slidably installed in the sliding cavity, a third sealing structure is arranged between the third piston and the sliding cavity, a protruding part with an outer diameter smaller than that of the third piston is integrally formed at one end of the third piston, a concave cavity for the protruding part to insert and slide is arranged inside the other end of the first connection seat, a fourth sealing structure is arranged between the protruding part and the concave cavity, one end of the first connector is inserted into the sliding cavity, a circular convex edge is arranged on the outer wall of the other end of the first connector, the circular convex edge is fixed to the end of one end of the first connection seat, a first annular step is arranged on the inner wall of one end of the first connector, the sealing ring group is embedded in the first annular step and abuts against the first annular step, the other end of the third piston is inserted into the first annular step and is used for squeezing the sealing ring group when the third piston moves towards the first connector, a jack for one end of the pipeline to be measured to insert is arranged in the first connector, a slot for one end of the pipeline to be measured to insert is arranged at the other end of the third piston when the third piston moves towards the first connector, an air inlet hole is arranged at the other end of the first connection seat, a gas guiding channel penetrating through the protruding part and the third piston and used for connecting the air inlet hole and the jack is arranged in the protruding part, a ring-shaped first sealing cavity is formed between the third sealing structure and the fourth sealing structure, a first air inlet hole is arranged in the first connection seat, one end of the first air inlet hole is communicated with the first sealing cavity, the other end of the first air inlet hole forms a first air inlet, when compressed air enters the first air inlet, the third piston is used for moving towards the first connector and squeezing the sealing ring group so that the sealing ring group deforms and is tightened against the inner wall of the first connector and the outer wall of the pipeline to be measured, the air inlet pressure of the first air inlet is greater than the air inlet pressure of the air inlet hole, the air inlet hole in one of the outer wrapping type pipeline end sealing joints in each pair of pipeline end sealing connection devices is blocked by a plug, and the air inlet holes in the other outer wrapping type pipeline end sealing joints in each pair of pipeline end sealing connection devices are all connected with the first air outlet channel in the corresponding differential pressure detection combined type cut-off valve; when the outer wrapping type pipeline end sealing joint is hermetically connected with the end of the pipeline to be measured, the end of the pipeline to be measured can be inserted into the first connector and the sealing ring group, and under the action of the third piston, the third piston can push the sealing ring group so that the sealing ring group deforms and is tightened against the inner wall of the first connector and the outer wall of the pipeline to be measured. In this way, compared with the traditional sealing method of abutting against the end, it has the advantages of good sealing effect and high reliability with the end of the pipeline to be measured, that is, it can effectively avoid leakage between the first connector and the end of the pipeline to be measured, thereby improving the accuracy and reliability of the airtightness detection of the pipeline to be measured.

[0012] The pipeline airtightness detection device of the present invention, wherein, an annular rib is provided on the end surface of the other end of the third piston, and the annular rib is used to abut against and squeeze the sealing ring group; after the annular rib is provided on the other end of the third piston, when the third piston moves towards the side of the sealing ring group, the annular rib can squeeze the sealing ring group, so that the sealing ring group can better deform, and thus the sealing ring group can better expand and tighten against the inner wall of the first connector and the outer wall of the pipeline to be measured; a support ring made of a metal material and for the end of the pipeline to be measured to pass through is embedded between the inner bottom of the first annular step and the sealing ring group. One side of the support ring abuts against the inner bottom of the first annular step, and the other side of the support ring abuts against the sealing ring group. The support ring is used to support the sealing ring group; through the arrangement of the support ring, when the third piston moves towards the side of the sealing ring group and squeezes the sealing ring group, the sealing ring group can better deform, and thus the sealing ring group can better expand and tighten against the inner wall of the first connector and the outer wall of the pipeline to be measured; the sealing ring group includes a plurality of coaxially arranged second sealing rings, and the plurality of second sealing rings are all embedded in the first annular step, and every two adjacent second sealing rings abut against each other; by adopting such a sealing ring group, when the third piston moves towards the side of the sealing ring group and squeezes the sealing ring group, the sealing ring group can better expand and tighten against the inner wall of the first connector and the outer wall of the pipeline to be measured, that is, the sealing effect between the first connector and the pipeline to be measured can be improved; the third sealing structure includes a third sealing ring. A second annular groove is provided on the outer wall of the third piston, and the third sealing ring is embedded in the second annular groove. The third sealing ring is in close contact and sealed with both the second annular groove and the inner wall of the sliding cavity; by adopting such a third sealing structure, reliable sealing can be achieved between the third piston and the first connecting seat; a fifth vent hole is provided on the side wall of the first connecting seat, and the fifth vent hole is used to communicate with the sliding cavity located between the third sealing ring and the first connector; through the arrangement of the fifth vent hole, when the third piston moves towards the side of the sealing ring group and squeezes the sealing ring group, the air in the sliding cavity located between the third sealing ring and the first connector can be discharged through the fifth vent hole. Similarly, when the third piston moves towards the side away from the sealing ring group, the air in the external environment can enter the sliding cavity located between the third sealing ring and the first connector through the fifth vent hole. In this way, the air pressure balance in the sliding cavity located between the third sealing ring and the first connector can be ensured, so that the third piston can move more smoothly in the sliding cavity; the fourth sealing structure includes a fourth sealing ring and a fifth sealing ring. A third annular groove and a fourth annular groove are provided on the outer wall of the protruding part. The third annular groove and the fourth annular groove are distributed along the axial direction of the protruding part. The fourth sealing ring and the fifth sealing ring are respectively embedded in the third annular groove and the fourth annular groove. The fourth sealing ring is in close contact and sealed with both the third annular groove and the inner wall of the concave cavity, and the fifth sealing ring is in close contact and sealed with both the fourth annular groove and the inner wall of the concave cavity;After adopting this fourth sealing structure, reliable sealing can be achieved between the protruding part and the concave cavity; a second annular groove is provided on the outer wall of the protruding part located between the third annular groove and the fourth annular groove, and a sixth ventilation hole is provided on the side wall of the first connecting seat, and the sixth ventilation hole is used to communicate with the second annular groove; through the setting of the sixth ventilation hole, when the third piston slides in the sliding cavity, the air in the second annular groove can be discharged outside the first connecting seat through the sixth ventilation hole, or the air in the external environment can enter the second annular groove through the sixth ventilation hole. In this way, the air pressure balance between the fourth sealing ring and the fifth sealing ring can be ensured, so that the third piston can move more smoothly in the sliding cavity; a plurality of arc-shaped holes evenly distributed in the circumferential direction are provided in the annular convex edge, and threaded holes corresponding to each arc-shaped hole are provided at the end of one end of the first connecting seat. One end of each arc-shaped hole is provided with a small-diameter part, and the other end of each arc-shaped hole is provided with a large-diameter part. The first connecting head is fixed to the first connecting seat by bolts passing through the small-diameter part and threadedly connected to the threaded holes. The inner diameter of each small-diameter part is larger than the outer diameter of the screw part of the bolt and smaller than the outer diameter of the head of the bolt. The inner diameter of each large-diameter part is larger than the outer diameter of the head of the bolt; after adopting this structure, after each bolt is loosened, the first connecting head can be rotated so that each large-diameter part is aligned with the bolt at the corresponding position. Moreover, since the inner diameter of each large-diameter part is larger than the outer diameter of the head of the bolt, in this way, the first connecting head can be detached from the first connecting seat by pulling the first connecting head, so that the replacement of the sealing ring group can be conveniently realized; after the replacement of the sealing ring group is completed, one end of the first connecting head can be inserted into the sliding cavity again, and the head of each bolt can pass through the large-diameter part at the corresponding position. Then, by rotating the first connecting head, each small-diameter part can be aligned with the bolt at the corresponding position. Finally, by tightening each bolt, the first connecting head can be re-fixed to the first connecting seat; an annular conical surface is provided on the inner wall of the jack away from the first annular step, and the annular conical surface is used to cooperate with the end of the pipeline to be measured for guiding so that the end of the pipeline to be measured can be inserted into the jack and pass through the jack; after the annular conical surface is provided on the inner wall of the jack away from the first annular step, when the end of the pipeline to be measured is to be inserted into the jack, the end of the pipeline to be measured can cooperate with the annular conical surface for guiding so that the end of the pipeline to be measured can be inserted into the jack and pass through the jack.;

[0013] When the outsourced pipeline end sealing joint is in use, first insert the end of the pipeline to be measured into the first connector and the sealing ring group. Then, let the compressed air supply pipe input compressed air into the first air inlet hole. When there is compressed air entering the first air inlet hole, the compressed air can enter the first sealing cavity. At this time, the third piston can move towards the side of the sealing ring group and squeeze the sealing ring group so that the sealing ring group deforms and expands tightly against the inner wall of the first connector and the outer wall of the pipeline to be measured. At this time, a sealed connection can be achieved between the first connector and the end of the pipeline to be measured. When the compressed air supply pipe connected to the first air inlet stops supplying compressed air into the first air inlet and the first air inlet discharges air through the air release valve, under the action of the resilience of the sealing ring group, the third piston can slide back towards the side away from the sealing ring group. In this way, the sealing ring group can be released from expanding tightly against the inner wall of the first connector and the outer wall of the pipeline to be measured, that is, the seal between the first connector and the pipeline to be measured can be released. Finally, just remove the end of the pipeline to be measured from the sealing ring group and the first connector.

[0014] The pipeline airtightness detection device of the present invention, wherein the inner expansion type pipeline end sealing joint includes a second connecting seat, a second connecting head, a sliding sleeve and a third sealing ring; a seventh air vent is provided in the second connecting seat, an eighth air vent is coaxially provided in the second connecting head, one end of the second connecting head is inserted into the second connecting seat and fixed to the second connecting seat, a fifth sealing structure is provided between one end of the second connecting head and the second connecting seat, the other end of the second connecting head is used to be inserted into one end of the pipeline to be tested, one end of the seventh air vent is communicated with one end of the eighth air vent, and the other end of the seventh air vent forms an air inlet; a second annular step is provided on the outer wall of the other end of the second connecting head, and the third sealing ring is sleeved outside the other end of the second connecting head and abuts against the second annular step; one end of the sliding sleeve is slidably sleeved outside the second connecting head and a sixth sealing structure is provided between the sliding sleeve and the second connecting head, and the other end of the sliding sleeve is slidably sleeved outside the second connecting seat and a seventh sealing structure is provided between the sliding sleeve and the second connecting seat; the fifth sealing structure, the sixth sealing structure and the seventh sealing structure enclose an annular second sealing cavity, a second air inlet hole is provided in the second connecting seat, one end of the second air inlet hole is communicated with the second sealing cavity, and the other end of the second air inlet hole forms a second air inlet. When compressed air enters the second air inlet, one end of the sliding sleeve is used to move towards one side of the third sealing ring and squeeze the third sealing ring so that the third sealing ring deforms and expands tightly against the outer wall of the second connecting head and the inner wall of the pipeline to be tested; the inlet pressure of the second air inlet is greater than the inlet pressure of the air inlet, the air inlet of one of the inner expansion type pipeline end sealing joints in each pair of pipeline end sealing connection devices is blocked by a plug, and the air inlets of the other inner expansion type pipeline end sealing joints in each pair of pipeline end sealing connection devices are all connected to the first air outlet channel in the corresponding differential pressure detection combined isolation valve; by adopting such an inner expansion type pipeline end sealing joint, when the inner expansion type pipeline end sealing joint is hermetically connected to the end of the pipeline to be tested, the other end of the second connecting head can be inserted into the end of the pipeline to be tested, and under the action of the sliding sleeve, the sliding sleeve can push the third sealing ring so that the third sealing ring deforms and expands tightly against the outer wall of the second connecting head and the inner wall of the pipeline to be tested. In this way, compared with the traditional sealing method of abutting against the end, it has the advantages of good sealing effect and high reliability with the end of the pipeline to be tested, that is, it can effectively avoid leakage between the second connecting head and the end of the pipeline to be tested, thereby improving the accuracy and reliability of the airtightness detection of the pipeline to be tested.

[0015] The pipeline airtightness detection device of the present invention, wherein, one end of the second connector is coaxially provided with a threaded joint having an outer diameter smaller than that of the second connector, and an internal thread is provided on the inner wall of the second connection seat, and the threaded joint is threadedly connected to the internal thread; after adopting this structure, one end of the second connector can be reliably fixedly connected to the first connection seat; a countersunk head in the shape of a regular hexagon is provided on the inner wall of the other end of the second connector; after providing a countersunk head in the shape of a regular hexagon on the inner wall of the other end of the second connector, when one end of the second connector is threadedly connected to the second connection seat, an external hexagonal wrench can be inserted into the countersunk head and the second connector can be screwed by the external hexagonal wrench, so that one end of the second connector can be conveniently threadedly connected to the second connection seat; an annular chamfer surface is provided on the outer wall of the other end of the second connector for guiding the cooperation with the inner wall of the pipeline to be measured so that the other end of the second connector can be inserted into the pipeline to be measured; after providing an annular chamfer surface on the outer wall of the other end of the second connector, during the process of inserting the other end of the second connector into the pipeline to be measured, the annular chamfer surface can guide the cooperation with the inner wall of the pipeline to be measured so that the other end of the second connector can be inserted into the pipeline to be measured; the fifth sealing structure includes a sixth sealing ring, a fifth annular groove is provided on the outer wall of one end of the second connector, the sixth sealing ring is embedded in the fifth annular groove, and the sixth sealing ring is in close contact and sealed with the fifth annular groove and the second connection seat; after adopting this fifth sealing structure, reliable sealing can be achieved between one end of the second connector and the second connection seat; the sixth sealing structure includes a seventh sealing ring, a sixth annular groove is provided on the inner wall of one end of the sliding sleeve, the seventh sealing ring is embedded in the sixth annular groove, and the seventh sealing ring is in close contact and sealed with the sixth annular groove and the outer wall of the second connector; after adopting this sixth sealing structure, reliable sealing can be achieved between one end of the sliding sleeve and the outer wall of the second connector; the seventh sealing structure includes an eighth sealing ring, a seventh annular groove is provided on the outer wall of the second connection seat, the eighth sealing ring is embedded in the seventh annular groove, and the eighth sealing ring is in close contact and sealed with the seventh annular groove and the inner wall of the other end of the sliding sleeve; after adopting this seventh sealing structure, reliable sealing can be achieved between the other end of the sliding sleeve and the second connection seat; a push sleeve made of a metal material is slidably sleeved on the outside of the second connector between the third sealing ring and the sliding sleeve, one end of the push sleeve is used to abut against the third sealing ring, and the other end of the push sleeve is used to abut against one end of the sliding sleeve; after sleeving a push sleeve made of a metal material on the outside of the second connector between the third sealing ring and the sliding sleeve, when the sliding sleeve moves towards the side of the third sealing ring, the sliding sleeve can push the push sleeve, and the push sleeve can reliably push the third sealing ring, so that the third sealing ring can be better deformed to make the third sealing ring more reliably expand and tighten with the outer wall of the second connector and the inner wall of the pipeline to be measured.

[0016] When the internal expansion type pipe end sealing joint is in use, first, the other end of the second connector and the third sealing ring located at the other end of the second connector are inserted into the end of the pipeline to be measured. Then, the compressed air supply pipe inputs compressed air into the second air inlet hole. When compressed air enters the second air inlet hole, the compressed air can enter the second sealing cavity. At this time, one end of the sliding sleeve can move towards one side of the third sealing ring and squeeze the third sealing ring so that the third sealing ring deforms and expands tightly against the outer wall of the second connector and the inner wall of the pipeline to be measured. At this time, a sealed connection can be achieved between the second connector and the end of the pipeline to be measured. When the compressed air supply pipe connected to the second air inlet stops supplying compressed air into the second air inlet hole, and the second air inlet discharges air through the air release valve, under the action of the resilience of the third sealing ring, the pushing sleeve and the sliding sleeve can slide and reset towards the side away from the third sealing ring. In this way, the third sealing ring can be disengaged from the outer wall of the second connector and the inner wall of the pipeline to be measured, that is, the seal between the second connector and the pipeline to be measured can be released. Finally, the other end of the second connector and the third sealing ring located at the other end of the second connector can be removed from the end of the pipeline to be measured.

[0017] Through the setting of several differential pressure detection combined isolating valves, each differential pressure detection combined isolating valve can simultaneously control the inflation and stop inflation of the pipeline to be measured and the standard pipeline, thus having the advantage of simple control and being able to simplify the structure of the pipeline airtightness detection equipment. In addition, the present invention can automatically detect the airtightness of the pipeline to be measured, having the advantages of high automation and convenient detection of the airtightness of the pipeline to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0019] Figure 1 is a three-dimensional structural schematic diagram of the present invention;

[0020] Figure 2 is Figure 1 an enlarged structural schematic diagram of part A in

[0021] Figure 3 is a first three-dimensional structural schematic diagram of the differential pressure detection combined isolating valve;

[0022] Figure 4 is a second three-dimensional structural schematic diagram of the differential pressure detection combined isolating valve;

[0023] Figure 5 is a front view structural schematic diagram of the differential pressure detection combined isolating valve;

[0024] Figure 6 It is the first three-dimensional sectional structural schematic diagram of the differential pressure detection combined isolation valve;

[0025] Figure 7 It is the second three-dimensional sectional structural schematic diagram of the differential pressure detection combined isolation valve;

[0026] Figure 8 It is the sectional structural schematic diagram of the differential pressure detection combined isolation valve;

[0027] Figure 9 It is Figure 8 The enlarged structural schematic diagram at position B in

[0028] Figure 10 It is Figure 8 The enlarged structural schematic diagram at position C in

[0029] Figure 11 It is the partial exploded three-dimensional structural schematic diagram of the differential pressure detection combined isolation valve;

[0030] Figure 12 It is the first three-dimensional structural schematic diagram of the outer wrapping type pipe end sealing joint;

[0031] Figure 13 It is the second three-dimensional structural schematic diagram of the outer wrapping type pipe end sealing joint;

[0032] Figure 14 It is the sectional structural schematic diagram of the outer wrapping type pipe end sealing joint;

[0033] Figure 15 It is Figure 14 The enlarged structural schematic diagram at position D in

[0034] Figure 16 It is the first three-dimensional structural schematic diagram of the inner expansion type pipe end sealing joint;

[0035] Figure 17 It is the second three-dimensional structural schematic diagram of the inner expansion type pipe end sealing joint;

[0036] Figure 18 It is the sectional structural schematic diagram of the inner expansion type pipe end sealing joint. Detailed implementation manners

[0037] The following will disclose multiple implementation manners of the present invention with diagrams. For the sake of clear illustration, many practical details will be described together in the following narrative. However, it should be understood that these practical details are not used to limit the present invention. That is to say, in some implementation manners of the present invention, these practical details are not necessary. In addition, for the sake of simplifying the diagrams, some conventional structures and components will be shown in a simple schematic manner in the diagrams.

[0038] In addition, in the present invention, descriptions such as "first", "second", etc. are only for descriptive purposes, and do not particularly refer to the meaning of order or sequence, nor are they used to limit the present invention. They are merely used to distinguish components or operations described with the same technical terms, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] As Figure 1 - 18 shown, the pipeline airtightness detection device of the present invention includes a frame 1, a plurality of differential pressure detection combined isolation valves 2, and a plurality of air pressure difference detection sensors. The plurality of differential pressure detection combined isolation valves 2 and the plurality of air pressure difference detection sensors correspond to each measured pipeline 3 one by one. A standard pipeline 4 corresponding to each measured pipeline 3 is fixed on the frame 1; a plurality of pairs of pipeline end sealing connection devices are installed on the frame 1. The two pipeline end sealing units in each pair of pipeline end sealing connection devices are respectively installed on the frame 1 at the positions of the two ends of the corresponding measured pipeline 3. Each pipeline end sealing unit is used to seal and connect one end of the measured pipeline 3 at the corresponding position. One of the pipeline end sealing units in each pair of pipeline end sealing connection devices is used to block one end of the measured pipeline 3, and the other pipeline end sealing unit in each pair of pipeline end sealing connection devices is connected to the first air outlet channel in the corresponding differential pressure detection combined isolation valve 2. One end of each standard pipeline 4 is blocked, and the other end of each standard pipeline 4 is connected to the second air outlet channel in the corresponding differential pressure detection combined isolation valve 2. The other end of each standard pipeline can be connected to the second air outlet channel in the corresponding differential pressure detection combined isolation valve through a pipeline. The two air inlet ends of each air pressure difference detection sensor are respectively connected to the first air outlet channel and the second air outlet channel in the corresponding differential pressure detection combined isolation valve 2; in the above structure, for the placement and removal of each measured pipeline, an independent electromagnet can be used for adsorption. For example, a support frame is installed on a manipulator, and electromagnets corresponding to each measured pipeline are installed at the bottom of the support frame. When the electromagnet is energized, the electromagnet can magnetically adsorb the measured pipeline, and when the electromagnet is de-energized, the electromagnet can release the measured pipeline. In this way, the movement of the measured pipeline can be conveniently realized.

[0040] Each differential pressure detection combined isolation valve 2 includes a base 21, a first valve seat 22, a first cylinder 23 and a first piston 24; the lower end of the first valve seat 22 is fixed on the base 21, and a first sealing structure is provided between the lower end of the first valve seat 22 and the base 21. A cavity 25 is formed between the first valve seat 22 and the base 21. The first cylinder 23 is fixed to the upper end of the first valve seat 22. The first piston 24 is vertically slidably disposed in the first valve seat 22. The lower end of the first piston 24 extends into the cavity 25. A second sealing structure is provided between the first piston 24 and the first valve seat 22. The upper end of the first piston 24 is connected to the driving end of the first cylinder 23. An air inlet passage 211, a first air outlet passage 212 and a second air outlet passage 213 are provided in the base 21. One end of the air inlet passage 211, one end of the first air outlet passage 212 and one end of the second air outlet passage 213 are all communicated with the cavity 25. The other end of the air inlet passage 211 is used for connecting with an air inlet pipe. The other end of the first air outlet passage 212 is used for connecting with another pipe end sealing unit in the corresponding pipe end sealing device. The other end of the second air outlet passage 213 is used for connecting with the other end of the corresponding standard pipe 4. A sealing gasket 241 is embedded at the lower end of the first piston 24. After the first cylinder 23 drives the first piston 24 to move downward, the sealing gasket 241 is used to abut against the upper end surface of the base 21 and is used to block one end of the first air outlet passage 212 and one end of the second air outlet passage 213. A first vent hole 214 and a second vent hole 215 are further provided on the base 21. One end of the first vent hole 214 and one end of the second vent hole 215 are respectively communicated with the first air outlet passage 212 and the second air outlet passage 213. The other end of the first vent hole 214 is used for connecting with one of the air inlets of the corresponding differential pressure detection sensor. The other end of the second vent hole 215 is used for connecting with the other air inlet of the corresponding differential pressure detection sensor; by adopting this differential pressure detection combined isolation valve, the inflation and stop of inflation of the measured pipe and the standard pipe can be controlled simultaneously.

[0041] The outer edges of one end of the first air outlet passage 212 and the outer edges of one end of the second air outlet passage 213 both protrude from the upper end surface of the base 21; after setting the outer edges of one end of the first air outlet passage and the outer edges of one end of the second air outlet passage to protrude from the upper end surface of the base, after the first cylinder drives the first piston to move downward, the outer edges of one end of the first air outlet passage and the outer edges of one end of the second air outlet passage can better squeeze the gasket, so that the gasket can more reliably block one end of the first air outlet passage and one end of the second air outlet passage; the first sealing structure includes a first sealing ring 221, a ring-shaped boss 222 is provided on the lower end surface of the first valve seat 22, a first annular groove 216 is provided on the upper end surface of the base 21, the first sealing ring 221 is fitted in the first annular groove 216, and the ring-shaped boss 222 is inserted into the first annular groove 216 and is used to press the first sealing ring 221, and the first sealing ring 221 is in close contact and sealed with both the first annular groove 216 and the ring-shaped boss 222; after adopting this first sealing structure, after the first valve seat is assembled on the base, reliable sealing can be achieved between the lower end of the first valve seat and the base; the second sealing structure includes a plurality of second sealing rings 242 distributed along the axial direction of the first piston 24, a first annular embedding groove 243 corresponding to each second sealing ring 242 is provided on the outer wall of the first piston 24, each second sealing ring 242 is fitted in the first annular embedding groove 243 at the corresponding position, and each second sealing ring 242 is in close contact and sealed with the inner wall of the first valve seat 22 and the first annular embedding groove 243 at the corresponding position; after adopting this second sealing structure, reliable sealing can be achieved between the first piston and the first valve seat; a "T"-shaped clamping groove 244 is provided at the upper end of the first piston 24, a "T"-shaped clamping block 231 is provided at the driving end of the first cylinder 23, and the clamping block 231 is engaged with the clamping groove 244; after adopting this structure, the upper end of the first piston can be reliably connected to the driving end of the first cylinder, and when the driving end of the first cylinder contracts, the first cylinder can drive the first piston to move upward, and when the driving end of the first cylinder extends, the first cylinder can drive the first piston to move downward.

[0042] The differential pressure detection combined isolation valve 2 further includes a second valve seat 26, a second cylinder 27 and a second piston 28. The lower end of the second valve seat 26 is fixed on the base 21. The second cylinder 27 is fixed to the upper end of the second valve seat 26. The second piston 28 is slidably installed vertically in the second valve seat 26. The upper end of the second piston 28 is fixed to the driving end of the second cylinder 27. A plug rod 281 with an outer diameter smaller than that of the second piston 28 is provided at the lower end of the second piston 28. A first sealing ring 282 is sleeved outside the plug rod 281. A third ventilation hole 217 is provided in the base 21. One end of the third ventilation hole 217 is communicated with the first air outlet channel 212. After the second cylinder 27 drives the second piston 28 to move downward, the lower end of the plug rod 281 is used to insert into the other end of the third ventilation hole 217, and the first sealing ring 282 is used to abut against the upper end surface of the base 21 and block the third ventilation hole 217. An exhaust joint 261 is connected to the side wall of the second valve seat 26. After the second cylinder 27 drives the second piston 28 to move upward, the exhaust joint 261 is used to communicate with the third ventilation hole 217 through the second valve seat 26; By adopting this structure, after the detection of the pipeline to be measured is completed, when the second cylinder drives the second piston to move upward, the sealing ring can release the blockage of the third ventilation hole. At this time, the compressed air filled in the pipeline to be measured can be discharged in sequence through the first air outlet channel, the third ventilation hole, the second valve seat and the exhaust joint. In this way, when the exhaust joint is connected to one end of the blow pipe and one end of the blow pipe is arranged in the pipeline end chamfering mechanism, the compressed air blown out through the blow pipe can blow out the metal debris in the pipeline end chamfering mechanism, that is, the reuse of the compressed air is realized to achieve the purpose of energy saving; The outer edge of the other end of the third ventilation hole 217 protrudes from the upper end surface of the base 21; By adopting this structure, after the second cylinder drives the second piston to move downward, the outer edge of the other end of the third ventilation hole can better squeeze the first sealing ring. In this way, the first sealing ring can better block the third ventilation hole.

[0043] A fourth ventilation hole 218 is further provided on the base 21. One end of the fourth ventilation hole 218 is communicated with the first air outlet channel 212. The other end of the fourth ventilation hole 218 is used to connect with a pressure gauge; By adopting this structure, the staff can clearly know the real-time air pressure in the first air outlet channel through the pressure gauge.

[0044] When the above differential pressure detection combined isolation valve is working, first, the driving end of the second cylinder drives the second piston to move downward so that the first sealing ring seals the third air vent. Then, the driving end of the first cylinder drives the first piston to move upward so that the sealing gasket releases the sealing of one end of the first air outlet channel and one end of the second air outlet channel. At this time, the compressed air from the air inlet pipe can enter the cavity through the air inlet channel. The compressed air entering the cavity can be filled into the pipeline to be measured through the first air outlet channel, and the compressed air entering the cavity can be filled into the standard pipeline through the second air outlet channel. After the pipeline to be measured and the standard pipeline are filled with air (usually, a time delay method can be used to ensure that the pipeline to be measured and the standard pipeline are filled with air), the driving end of the first cylinder drives the first piston to move downward so that the sealing gasket seals one end of the first air outlet channel and one end of the second air outlet channel. At this time, the air inlet channel, one end of the first air outlet channel, and one end of the second air outlet channel are not connected to each other. Then, the differential pressure detection sensor starts to detect the pressure difference between the first air outlet channel and the second air outlet channel. If the pressure difference between the first air outlet channel and the second air outlet channel is less than the preset value, it means that there is no leakage in the pipeline to be measured (because there must be no leakage in the standard pipeline). If the pressure difference between the first air outlet channel and the second air outlet channel is greater than the preset value, it means that there is a leakage in the pipeline to be measured (because there must be no leakage in the standard pipeline). In this way, the pipeline to be measured is unqualified. Then, during the subsequent operation of the pipeline airtightness detection equipment, the unqualified pipeline can be placed in the unqualified area. After the above detection is completed, the second cylinder can drive the second piston to move upward. When the second piston moves upward, the first sealing ring can release the sealing of the third air vent. At this time, the compressed air filled in the pipeline to be measured can be discharged in sequence through the first air outlet channel, the third air vent, the second valve seat, the exhaust joint, and the blow pipe. In this way, the compressed air blown out through the blow pipe can blow out the metal chips in the pipeline end chamfering mechanism, that is, the compressed air is reused to achieve the purpose of energy saving.

[0045] Each pipeline end sealing unit includes a sliding seat 51 and a third cylinder 52. The sliding seat 51 is slidably connected to the frame 1 through a slide rail assembly 53. The third cylinder 52 is fixed to the frame 1. The sliding seat 51 is fixed to the piston rod of the third cylinder 52. Each pipeline end sealing unit further includes an outer wrapped pipeline end sealing joint 6 or an inner expanding pipeline end sealing joint 7 fixed to the inner end face of the sliding seat 51. The third cylinder 52 is used to drive the sliding seat 51 to move along the axial direction of the pipeline to be measured 3 so that the outer wrapped pipeline end sealing joint 6 or the inner expanding pipeline end sealing joint 7 approaches or moves away from the pipeline to be measured 3. When the outer wrapped pipeline end sealing joint 6 or the inner expanding pipeline end sealing joint 7 approaches the pipeline to be measured 3, the outer wrapped pipeline end sealing joint 6 or the inner expanding pipeline end sealing joint 7 is used for sealing connection with the end of the pipeline to be measured 3; one of the outer wrapped pipeline end sealing joints 6 or the inner expanding pipeline end sealing joints 7 in each pair of pipeline end sealing connection devices is used for blocking one end of the pipeline to be measured 3, and the other outer wrapped pipeline end sealing joint 6 or the inner expanding pipeline end sealing joint 7 in each pair of pipeline end sealing connection devices is connected to the first air outlet channel 212 in the corresponding differential pressure detection combined isolation valve 2; after adopting this structure, when the piston rod of the third cylinder extends, the third cylinder can drive the sliding seat to slide so that the outer wrapped pipeline end sealing joint or the inner expanding pipeline end sealing joint installed on the sliding seat is in sealing connection with the end of the pipeline to be measured. When the piston rod of the third cylinder contracts, the third cylinder can drive the sliding seat to slide so that the outer wrapped pipeline end sealing joint or the inner expanding pipeline end sealing joint installed on the sliding seat disengages from the pipeline to be measured.

[0046] The externally wrapped pipe end sealing joint 6 includes a first connection seat 61, a first connection head 62, a third piston 63 and a sealing ring group 64; a sliding cavity 611 is provided inside one end of the first connection seat 61, the third piston 63 is slidably installed in the sliding cavity 611, a third sealing structure is provided between the third piston 63 and the sliding cavity 611, a protruding portion 631 with an outer diameter smaller than that of the third piston 63 is integrally formed at one end of the third piston 63, a concave cavity 612 for the protruding portion 631 to insert and slide is provided inside the other end of the first connection seat 61, a fourth sealing structure is provided between the protruding portion 631 and the concave cavity 612, one end of the first connection head 62 is inserted into the sliding cavity 611, an annular convex edge 621 is provided on the outer wall of the other end of the first connection head 62, the annular convex edge 621 is fixed to the end of one end of the first connection seat 61, a first annular step 622 is provided on the inner wall of one end of the first connection head 62, the sealing ring group 64 is embedded in the first annular step 622 and abuts against the first annular step 622, the other end of the third piston 63 is inserted into the first annular step 622 and is used to squeeze the sealing ring group 64 when the third piston 63 moves towards the first connection head 62, a jack 623 for one end of the pipeline 3 to be measured to insert is provided in the first connection head 62, a slot 632 for one end of the pipeline to be measured to insert is provided at the other end of the third piston 63 when the third piston 63 moves towards the first connection head 62, an air inlet hole 613 is provided at the other end of the first connection seat 61, a gas guiding channel 633 which penetrates through the protruding portion 631 and the third piston 63 and is used to connect the air inlet hole 613 and the jack 623 is provided in the protruding portion 631, a ring-shaped first sealing cavity 65 is formed between the third sealing structure and the fourth sealing structure, a first air inlet hole 614 is provided in the first connection seat 61, one end of the first air inlet hole 614 is communicated with the first sealing cavity 65, the other end of the first air inlet hole 614 forms a first air inlet 615, when compressed air enters through the first air inlet 615, the third piston 63 is used to move towards the first connection head 62 and squeeze the sealing ring group 64 so that the sealing ring group 64 deforms and is tightened against the inner wall of the first connection head 62 and the outer wall of the pipeline 3 to be measured, the inlet pressure of the first air inlet 615 is greater than the inlet pressure of the air inlet hole 613, the air inlet hole 613 in one of the externally wrapped pipe end sealing joints 6 in each pair of pipe end sealing connection devices is blocked by a plug, the air inlet holes 613 in the other externally wrapped pipe end sealing joints 6 in each pair of pipe end sealing connection devices are all connected to the first air outlet channel 212 in the corresponding differential pressure detection combined isolation valve 2, and the air inlet hole can be connected to the first air outlet channel by a pipeline;When the external-packaged pipeline end sealing joint is hermetically connected to the end of the pipeline under test, the end of the pipeline under test can be inserted into the first connector and the sealing ring group. Under the action of the third piston, the third piston can push the sealing ring group to cause the sealing ring group to deform and expand tightly against the inner wall of the first connector and the outer wall of the pipeline under test. In this way, compared with the traditional sealing method using end abutment, it has the advantages of good sealing effect and high reliability with the end of the pipeline under test, that is, it can effectively avoid leakage between the first connector and the end of the pipeline under test, thereby improving the accuracy and reliability of the airtightness detection of the pipeline under test.

[0047] On the end face at the other end of the third piston 63, an annular rib 634 is provided. The annular rib 634 is used to abut against and squeeze the sealing ring group 64. After the annular rib is provided at the other end of the third piston, when the third piston moves towards the side of the sealing ring group, the annular rib can squeeze the sealing ring group. In this way, the sealing ring group can better deform, and thus the sealing ring group can better expand and tighten against the inner wall of the first connector and the outer wall of the pipeline to be measured. A support ring 66 made of a metal material and for the end of the pipeline to be measured to pass through is embedded between the inner bottom of the first annular step 622 and the sealing ring group 64. One side of the support ring 66 abuts against the inner bottom of the first annular step 622, and the other side of the support ring 66 abuts against the sealing ring group 64. The support ring 66 is used to support the sealing ring group 64. Through the arrangement of the support ring, when the third piston moves towards the side of the sealing ring group and squeezes the sealing ring group, the sealing ring group can better deform, and thus the sealing ring group can better expand and tighten against the inner wall of the first connector and the outer wall of the pipeline to be measured. The sealing ring group 64 includes a plurality of coaxially arranged second sealing rings 641. The plurality of second sealing rings 641 are all embedded in the first annular step 622, and every two adjacent second sealing rings 641 abut against each other. After adopting this kind of sealing ring group, when the third piston moves towards the side of the sealing ring group and squeezes the sealing ring group, the sealing ring group can better expand and tighten against the inner wall of the first connector and the outer wall of the pipeline to be measured, that is, the sealing effect between the first connector and the pipeline to be measured can be improved. The third sealing structure includes a third sealing ring 67. A second annular groove 635 is provided on the outer wall of the third piston 63. The third sealing ring 67 is embedded in the second annular groove 635, and the third sealing ring 67 is in close contact and sealed with both the inner wall of the second annular groove 635 and the inner wall of the sliding cavity 611. After adopting this kind of third sealing structure, reliable sealing can be achieved between the third piston and the first connection seat. A fifth vent hole 616 is provided on the side wall of the first connection seat 61. The fifth vent hole 616 is used to communicate with the sliding cavity 611 located between the third sealing ring 67 and the first connector 62. Through the arrangement of the fifth vent hole, when the third piston moves towards the side of the sealing ring group and squeezes the sealing ring group, the air in the sliding cavity located between the third sealing ring and the first connector can be discharged through the fifth vent hole. Similarly, when the third piston moves towards the side away from the sealing ring group, the air in the external environment can enter the sliding cavity located between the third sealing ring and the first connector through the fifth vent hole. In this way, the air pressure balance in the sliding cavity located between the third sealing ring and the first connector can be ensured, and thus the third piston can move more smoothly in the sliding cavity.The fourth sealing structure includes a fourth sealing ring 68 and a fifth sealing ring 69. A third annular groove 636 and a fourth annular groove 637 are provided on the outer wall of the protruding portion 631. The third annular groove 636 and the fourth annular groove 637 are distributed along the axial direction of the protruding portion 631. The fourth sealing ring 68 and the fifth sealing ring 69 are respectively installed in the third annular groove 636 and the fourth annular groove 637. The fourth sealing ring 68 is in close contact and sealed with both the inner wall of the third annular groove 636 and the inner wall of the concave cavity 612. The fifth sealing ring 69 is in close contact and sealed with both the inner wall of the fourth annular groove 637 and the inner wall of the concave cavity 612. After adopting this fourth sealing structure, reliable sealing can be achieved between the protruding portion and the concave cavity. A second annular groove 638 is provided on the outer wall of the protruding portion 631 between the third annular groove 636 and the fourth annular groove 637. A sixth vent hole 617 is provided on the side wall of the first connection seat 61. The sixth vent hole 617 is used to communicate with the second annular groove 638. Through the setting of the sixth vent hole, when the third piston slides in the sliding cavity, the air in the second annular groove can be discharged to the outside of the first connection seat through the sixth vent hole, or the air in the external environment can enter the second annular groove through the sixth vent hole. In this way, the air pressure balance between the fourth sealing ring and the fifth sealing ring can be ensured, so that the third piston can move more smoothly in the sliding cavity. A number of arc-shaped holes 624 evenly distributed in the circumferential direction are provided in the annular convex edge 621. Threaded holes 618 corresponding to each arc-shaped hole 624 are provided at one end of the first connection seat 61. A small-diameter portion 6241 is provided at one end of each arc-shaped hole 624, and a large-diameter portion 6242 is provided at the other end of each arc-shaped hole 624. The first connection head 62 is fixed to the first connection seat 61 by bolts passing through the small-diameter portion 6241 and threadedly connected to the threaded holes 618. The inner diameter of each small-diameter portion 6241 is larger than the outer diameter of the screw portion of the bolt and smaller than the outer diameter of the bolt head. The inner diameter of each large-diameter portion 6242 is larger than the outer diameter of the bolt head. After adopting this structure, after each bolt is loosened, the first connection head can be rotated so that each large-diameter portion is aligned with the bolt at the corresponding position. And since the inner diameter of each large-diameter portion is larger than the outer diameter of the bolt head, in this way, the first connection head can be detached from the first connection seat by pulling the first connection head, so that the replacement of the sealing ring group can be conveniently realized. After the replacement of the sealing ring group is completed, one end of the first connection head can be inserted into the sliding cavity again, and the head of each bolt can be made to pass through the large-diameter portion at the corresponding position. Then, by rotating the first connection head, each small-diameter portion can be aligned with the bolt at the corresponding position. Finally, by tightening each bolt, the first connection head can be fixed to the first connection seat again.An annular tapered surface 6231 is provided on the inner wall of the end of the jack 623 away from the first annular step 622. The annular tapered surface 6231 is used for guiding the cooperation with the end of the pipeline 3 to be measured so that the end of the pipeline 3 to be measured can be inserted into the jack 623 and pass through the jack 623; after the annular tapered surface is provided on the inner wall of the end of the jack away from the first annular step, when the end of the pipeline to be measured is to be inserted into the jack, the end of the pipeline to be measured can be guided in cooperation with the annular tapered surface so that the end of the pipeline to be measured can be inserted into the jack and pass through the jack.

[0048] When the external pipe end sealing joint is in use, first, the end of the pipeline to be measured is inserted into the first connector and the sealing ring group. Then, the compressed air supply pipe inputs compressed air into the first air inlet hole. When there is compressed air entering the first air inlet hole, the compressed air can enter the first sealing cavity. At this time, the third piston can move towards the side of the sealing ring group and squeeze the sealing ring group so that the sealing ring group deforms and expands tightly against the inner wall of the first connector and the outer wall of the pipeline to be measured. At this time, a sealed connection can be achieved between the first connector and the end of the pipeline to be measured; when the compressed air supply pipe connected to the first air inlet stops supplying compressed air into the first air inlet and the first air inlet is deflated through the air release valve, under the action of the resilience of the sealing ring group, the third piston can slide and reset towards the side away from the sealing ring group. In this way, the sealing ring group can be released from expanding tightly against the inner wall of the first connector and the outer wall of the pipeline to be measured, that is, the seal between the first connector and the pipeline to be measured can be released. Finally, the end of the pipeline to be measured can be removed from the sealing ring group and the first connector; in addition, the external pipe end sealing joint can be applicable to the pipeline to be measured with a smaller outer diameter.

[0049] The internal expansion type pipe end sealing joint 7 includes a second connecting seat 71, a second connecting head 72, a sliding sleeve 73 and a third sealing ring 74; a seventh ventilation hole 711 is provided in the second connecting seat 71, an eighth ventilation hole 721 is coaxially provided in the second connecting head 72, one end of the second connecting head 72 is inserted into the second connecting seat 71 and fixed to the second connecting seat 71, a fifth sealing structure is provided between one end of the second connecting head 72 and the second connecting seat 71, the other end of the second connecting head 72 is used for inserting into one end of the pipeline 3 to be measured, one end of the seventh ventilation hole 711 is communicated with one end of the eighth ventilation hole 721, and the other end of the seventh ventilation hole 711 forms an inflation port 712; a second annular step 722 is provided on the outer wall of the other end of the second connecting head 72, and the third sealing ring 74 is sleeved outside the other end of the second connecting head 72 and abuts against the second annular step 722; one end of the sliding sleeve 73 is slidably sleeved outside the second connecting head 72 and a sixth sealing structure is provided between the sliding sleeve 73 and the second connecting head 72, and the other end of the sliding sleeve 73 is slidably sleeved outside the second connecting seat 71 and a seventh sealing structure is provided between the sliding sleeve 73 and the second connecting seat 71; the fifth sealing structure, the sixth sealing structure and the seventh sealing structure enclose an annular second sealing cavity 75, a second air inlet hole 713 is provided in the second connecting seat 71, one end of the second air inlet hole 713 is communicated with the second sealing cavity 75, and the other end of the second air inlet hole 713 forms a second air inlet 714. When compressed air enters through the second air inlet 714, one end of the sliding sleeve 73 is used for moving towards the side of the third sealing ring 74 and extruding the third sealing ring 74 so that the third sealing ring 74 deforms and expands tightly against the outer wall of the second connecting head 72 and the inner wall of the pipeline 3 to be measured; the air inlet pressure of the second air inlet 714 is greater than the air inlet pressure of the inflation port 712. The inflation port 712 in one of the internal expansion type pipe end sealing joints 7 in each pair of pipe end sealing connection devices is blocked by a plug, and the inflation port 712 in the other internal expansion type pipe end sealing joint 7 in each pair of pipe end sealing connection devices is connected to the first air outlet channel 212 in the corresponding differential pressure detection combined isolation valve 2. The inflation port and the first air outlet channel can be connected by a pipeline; by adopting such an internal expansion type pipe end sealing joint, when the internal expansion type pipe end sealing joint is hermetically connected to the end of the pipeline to be measured, the other end of the second connecting head can be inserted into the end of the pipeline to be measured, and under the action of the sliding sleeve, the sliding sleeve can push the third sealing ring so that the third sealing ring deforms and expands tightly against the outer wall of the second connecting head and the inner wall of the pipeline to be measured. In this way, compared with the traditional sealing method of abutting against the end, it has the advantages of good sealing effect and high reliability with the end of the pipeline to be measured, that is, it can effectively avoid leakage between the second connecting head and the end of the pipeline to be measured, thereby improving the accuracy and reliability of the airtightness detection of the pipeline to be measured.

[0050] One end of the second connector 72 is coaxially provided with a threaded joint 723 whose outer diameter is smaller than that of the second connector 72. An internal thread 715 is provided on the inner wall of the second socket 71, and the threaded joint 723 is threadedly connected to the internal thread 715. After adopting this structure, one end of the second connector can be reliably fixedly connected to the first socket. On the inner wall of the other end of the second connector 72, there is a counterbore 724 in the shape of a regular hexagon. By providing a counterbore in the shape of a regular hexagon on the inner wall of the other end of the second connector, when one end of the second connector is threadedly connected to the second socket, an external hexagon wrench can be inserted into the counterbore and the second connector can be turned by the external hexagon wrench. In this way, it is possible to conveniently threadedly connect one end of the second connector to the second socket. On the outer wall of the other end of the second connector 72, there is an annular chamfer surface 725 for guiding the cooperation with the inner wall of the pipeline 3 to be measured so that the other end of the second connector 72 can be inserted into the pipeline 3 to be measured. By providing an annular chamfer surface on the outer wall of the other end of the second connector, during the process of inserting the other end of the second connector into the pipeline to be measured, the annular chamfer surface can guide the cooperation with the inner wall of the pipeline to be measured so that the other end of the second connector can be inserted into the pipeline to be measured. The fifth sealing structure includes a sixth sealing ring 76. On the outer wall of one end of the second connector 72, there is a fifth annular groove 726, and the sixth sealing ring 76 is fitted in the fifth annular groove 726. The sixth sealing ring 76 is in close contact and sealed with both the fifth annular groove 726 and the second socket 71. After adopting this fifth sealing structure, reliable sealing can be achieved between one end of the second connector and the second socket. The sixth sealing structure includes a seventh sealing ring 77. On the inner wall of one end of the sliding sleeve 73, there is a sixth annular groove 731, and the seventh sealing ring 77 is fitted in the sixth annular groove 731. The seventh sealing ring 77 is in close contact and sealed with both the sixth annular groove 731 and the outer wall of the second connector 72. After adopting this sixth sealing structure, reliable sealing can be achieved between one end of the sliding sleeve and the outer wall of the second connector. The seventh sealing structure includes an eighth sealing ring 78. On the outer wall of the second socket 71, there is a seventh annular groove 716, and the eighth sealing ring 78 is fitted in the seventh annular groove 716. The eighth sealing ring 78 is in close contact and sealed with both the seventh annular groove 716 and the inner wall of the other end of the sliding sleeve 73. After adopting this seventh sealing structure, reliable sealing can be achieved between the other end of the sliding sleeve and the second socket. A push sleeve 79 made of a metal material is slidably sleeved on the outside of the second connector 72 between the third sealing ring 74 and the sliding sleeve 73. One end of the push sleeve 79 is used to abut against the third sealing ring 74, and the other end of the push sleeve 79 is used to abut against one end of the sliding sleeve 73.After a pushing sleeve made of a metal material is sleeved outside the second connector between the third sealing ring and the sliding sleeve, when the sliding sleeve moves towards the side of the third sealing ring, the sliding sleeve can push the pushing sleeve, and the pushing sleeve can reliably push the third sealing ring. In this way, the third sealing ring can be better deformed, so that the third sealing ring can be more reliably tightened against the outer wall of the second connector and the inner wall of the pipeline to be measured.

[0051] When the internal expansion type pipeline end sealing joint is in use, first, the other end of the second connector and the third sealing ring located at the other end of the second connector are inserted into the end of the pipeline to be measured. Then, the compressed air supply pipe inputs compressed air into the second air inlet hole. When compressed air enters the second air inlet hole, the compressed air can enter the second sealing cavity. At this time, one end of the sliding sleeve can move towards the side of the third sealing ring and squeeze the third sealing ring to cause the third sealing ring to deform and be tightened against the outer wall of the second connector and the inner wall of the pipeline to be measured. At this time, a sealed connection can be achieved between the second connector and the end of the pipeline to be measured. When the compressed air supply pipe connected to the second air inlet stops supplying compressed air into the second air inlet hole and the second air inlet deflates through the air release valve, under the action of the resilience of the third sealing ring, the pushing sleeve and the sliding sleeve can slide and reset towards the side away from the third sealing ring. In this way, the third sealing ring can be released from being tightened against the outer wall of the second connector and the inner wall of the pipeline to be measured, that is, the seal between the second connector and the pipeline to be measured can be released. Finally, the other end of the second connector and the third sealing ring located at the other end of the second connector can be removed from the end of the pipeline to be measured. In addition, the internal expansion type pipeline end sealing joint can be applicable to pipelines to be measured with a smaller outer diameter.

[0052] When the present invention needs to detect the sealing performance of the tested pipeline, the two third cylinders in each pair of pipeline end sealing connection devices can drive the sliding seat to move toward one side of the tested pipeline so that the outward-wrapped pipeline end sealing joint or the inward-expanded pipeline end sealing joint installed on the sliding seat is sealed and connected to the end of the tested pipeline at the corresponding position. Then the driving end of the second cylinder in each pressure differential detection combined isolating valve drives the second piston to move downward so that the first sealing ring can seal the third vent. Then the driving end of the first cylinder in each pressure differential detection combined isolating valve drives the first piston to move upward so that the sealing gasket releases the sealing of one end of the first air outlet channel and one end of the second air outlet channel. At this time, the compressed air from the air inlet pipe can The compressed air enters the cavity through the air inlet channel, and the compressed air entering the cavity can be filled into the corresponding measured pipe through the first air outlet channel, and the compressed air entering the cavity can be filled into the corresponding standard pipe through the second air outlet channel. After the measured pipe and the standard pipe are inflated (generally, a delay method can be used to ensure that the measured pipe and the standard pipe are inflated), the driving end of the first cylinder in each pressure difference detection combined isolation valve drives the first piston to move downward so that the sealing gasket can block one end of the first air outlet channel and one end of the second air outlet channel. At this time, the air inlet channel, one end of the first air outlet channel and one end of the second air outlet channel are not connected to each other. Then, each air pressure difference detection sensor starts to detect the corresponding pressure difference detection group. The air pressure difference between the first air outlet channel and the second air outlet channel in the combined isolation valve is detected. If the air pressure difference between the first air outlet channel and the second air outlet channel is less than the preset value, it means that there is no leakage in the tested pipeline (because the standard pipeline definitely does not have leakage); if the air pressure difference between the first air outlet channel and the second air outlet channel is greater than the preset value, it means that there is leakage in the tested pipeline (because the standard pipeline definitely does not have leakage). In this way, the tested pipeline is unqualified. Then, in the subsequent work of the pipeline air tightness detection equipment, the unqualified tested pipeline can be placed in the unqualified area; after the above detection is completed, the second cylinder in each pressure difference detection combined isolation valve can drive the second piston When the second piston moves upward, the first sealing ring can release the blockage of the third vent hole. At this time, the compressed air filled in the measured pipeline can be discharged through the first air outlet channel, the third vent hole, the second valve seat, the exhaust joint and the air blowing pipe in sequence. In this way, the compressed air blown out through the air blowing pipe can realize the blowing away of metal debris in the chamfering mechanism of the pipeline end, that is, the compressed air is reused to achieve the purpose of energy saving. Finally, the two third cylinders in each pair of pipeline end sealing connection devices can drive the sliding seat to move toward the side away from the measured pipeline so that the outer package pipeline end sealing joint or the inner expansion pipeline end sealing joint installed on the sliding seat is separated from the end of the measured pipeline at the corresponding position;After the airtightness detection of the pipeline under test is completed, the manipulator can place the qualified pipelines under test into the qualified area and the unqualified pipelines under test into the unqualified area.;

[0053] The above are only the embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. An airtightness detection device for pipelines, characterized in that: It includes a frame (1), several differential pressure detection combined isolation valves (2) and several air pressure difference detection sensors. The several differential pressure detection combined isolation valves (2) and several air pressure difference detection sensors correspond to each measured pipeline (3) one by one. A standard pipeline (4) corresponding to each measured pipeline (3) is fixed on the frame (1); one end of each standard pipeline (4) is blocked, and the picking and placing of each measured pipeline are adsorbed by an independent electromagnet. Several pairs of pipeline end sealing connection devices are installed on the frame (1). The two pipeline end sealing units in each pair of pipeline end sealing connection devices are respectively installed on the frame (1) at the positions of the two ends of the corresponding measured pipeline (3) for sealing connection with one end of the measured pipeline (3) at the corresponding position. One of the pipeline end sealing units is used to block one end of the measured pipeline (3). Each differential pressure detection combined isolation valve (2) includes a base (21), a first valve seat (22), a first cylinder (23) and a first piston (24); the lower end of the first valve seat (22) is fixed on the base (21), and a first sealing structure is arranged between the lower end of the first valve seat (22) and the base (21). A cavity (25) is formed between the first valve seat (22) and the base (21). The first cylinder (23) is fixed on the upper end of the first valve seat (22). The first piston (24) is vertically slidably arranged in the first valve seat (22). The lower end of the first piston (24) extends into the cavity (25). A second sealing structure is arranged between the first piston (24) and the first valve seat (22). The upper end of the first piston (24) is connected to the driving end of the first cylinder (23). An air inlet channel (211), a first air outlet channel (212) and a second air outlet channel (213) are arranged in the base (21). One end of the air inlet channel (211), one end of the first air outlet channel (212) and one end of the second air outlet channel (213) are all communicated with the cavity (25). The other end of the air inlet channel (211) is used to connect with an air inlet pipe. The other end of the first air outlet channel (212) is used to connect with another pipeline end sealing unit in the corresponding pipeline end sealing connection device. The other end of the second air outlet channel (213) is used to connect with the other end of the corresponding standard pipeline (4). A sealing gasket (241) is embedded at the lower end of the first piston (24). After the first cylinder (23) drives the first piston (24) to move downward, the sealing gasket (241) is used to abut against the upper end surface of the base (21) and is used to block one end of the first air outlet channel (212) and one end of the second air outlet channel (213); the two air inlet ends of each air pressure difference detection sensor are respectively connected to the first air outlet channel and the second air outlet channel in the corresponding differential pressure detection combined isolation valve (2).

2. The pipeline airtightness detection device according to claim 1, characterized in that, The base (21) is further provided with a first ventilation hole (214) and a second ventilation hole (215). One end of the first ventilation hole (214) and one end of the second ventilation hole (215) are respectively communicated with the first air outlet channel (212) and the second air outlet channel (213). The other end of the first ventilation hole (214) is used to connect to one of the intake ends of the corresponding differential pressure detection sensors, and the other end of the second ventilation hole (215) is used to connect to the other intake end of the corresponding differential pressure detection sensors.

3. The pipeline airtightness detection device according to claim 2, characterized in that The outer edges of one end of the first air outlet channel (212) and one end of the second air outlet channel (213) both protrude from the upper end surface of the base (21); the first sealing structure includes a first sealing ring (221). An annular boss (222) is provided on the lower end surface of the first valve seat (22), and a first annular groove (216) is provided on the upper end surface of the base (21). The first sealing ring (221) is fitted in the first annular groove (216), and the annular boss (222) is inserted into the first annular groove (216) and used to press the first sealing ring (221). The first sealing ring (221) is in close contact and sealed with both the first annular groove (216) and the annular boss (222); the second sealing structure includes a plurality of second sealing rings (242) distributed along the axial direction of the first piston (24). First annular slots (243) corresponding to each of the second sealing rings (242) are provided on the outer wall of the first piston (24). Each of the second sealing rings (242) is fitted in the first annular slot (243) at the corresponding position, and each of the second sealing rings (242) is in close contact and sealed with the inner wall of the first valve seat (22) and the first annular slot (243) at the corresponding position; a "T"-shaped slot (244) is provided at the upper end of the first piston (24), and a "T"-shaped block (231) is provided at the driving end of the first cylinder (23). The block (231) is engaged with the slot (244) in a matching manner.

4. The pipeline airtightness detection device according to claim 2 or 3, characterized in that, The differential pressure detection combined isolation valve (2) further includes a second valve seat (26), a second cylinder (27) and a second piston (28). The lower end of the second valve seat (26) is fixed on the base (21). The second cylinder (27) is fixed to the upper end of the second valve seat (26). The second piston (28) is slidably mounted vertically in the second valve seat (26). The upper end of the second piston (28) is fixed to the driving end of the second cylinder (27). A plug rod (281) with an outer diameter smaller than that of the second piston (28) is provided at the lower end of the second piston (28). A first sealing ring (282) is sleeved outside the plug rod (281). A third ventilation hole (217) is provided in the base (21). One end of the third ventilation hole (217) is communicated with the first air outlet channel (212). After the second cylinder (27) drives the second piston (28) to move downward, the lower end of the plug rod (281) is used to insert into the other end of the third ventilation hole (217), and the first sealing ring (282) is used to abut against the upper end surface of the base (21) and block the third ventilation hole (217). An exhaust joint (261) is connected to the side wall of the second valve seat (26). After the second cylinder (27) drives the second piston (28) to move upward, the exhaust joint (261) is used to communicate with the third ventilation hole (217) through the second valve seat (26); the outer edge of the other end of the third ventilation hole (217) protrudes from the upper end surface of the base (21).

5. The pipeline airtightness detection device according to claim 4, characterized in that, A fourth ventilation hole (218) is further provided on the base (21). One end of the fourth ventilation hole (218) is communicated with the first air outlet channel (212). The other end of the fourth ventilation hole (218) is used to connect with a pressure gauge.

6. The pipeline airtightness detection device according to claim 2, characterized in that, Each of the pipe end sealing units includes a sliding seat (51) and a third cylinder (52). The sliding seat (51) is slidably connected to the frame (1) through a slide rail assembly (53). The third cylinder (52) is fixed to the frame (1). The sliding seat (51) is fixed to the piston rod of the third cylinder (52). Each of the pipe end sealing units further includes an outer wrapped pipe end sealing joint (6) or an inner expanding pipe end sealing joint (7) fixed to the inner end face of the sliding seat (51). The third cylinder (52) is used to drive the sliding seat (51) to move along the axial direction of the pipe under test (3) so that the outer wrapped pipe end sealing joint (6) or the inner expanding pipe end sealing joint (7) approaches or moves away from the pipe under test (3). When the outer wrapped pipe end sealing joint (6) or the inner expanding pipe end sealing joint (7) approaches the pipe under test (3), the outer wrapped pipe end sealing joint (6) or the inner expanding pipe end sealing joint (7) is used for sealing connection with the end of the pipe under test (3). One of the outer wrapped pipe end sealing joints (6) or the inner expanding pipe end sealing joints (7) in each pair of pipe end sealing connection devices is used to block one end of the pipe under test (3), and the other outer wrapped pipe end sealing joint (6) or the inner expanding pipe end sealing joint (7) in each pair of pipe end sealing connection devices is connected to the first air outlet channel (212) in the corresponding differential pressure detection combined cut-off valve (2).

7. The pipeline airtightness detection device according to claim 6, characterized in that, The external wrapping type pipe end sealing joint (6) includes a first connection seat (61), a first connector (62), a third piston (63), and a sealing ring group (64);Inside one end of the first connecting seat (61), a sliding cavity (611) is provided. The third piston (63) is slidably installed in the sliding cavity (611). A third sealing structure is provided between the third piston (63) and the sliding cavity (611). One end of the third piston (63) is integrally formed with a protruding portion (631) having an outer diameter smaller than that of the third piston (63). Inside the other end of the first connecting seat (61), a concave cavity (612) is provided for the protruding portion (631) to be inserted and slide therein. A fourth sealing structure is provided between the protruding portion (631) and the concave cavity (612). One end of the first connecting head (62) is inserted into the sliding cavity (611). An annular convex edge (621) is provided on the outer wall of the other end of the first connecting head (62). The annular convex edge (621) is fixed to the end of one end of the first connecting seat (61). A first annular step (622) is provided on the inner wall of one end of the first connecting head (62). The seal ring group (64) is installed in the first annular step (622) and abuts against the first annular step (622). The other end of the third piston (63) is inserted into the first annular step (622) and is used to squeeze the seal ring group (64) when the third piston (63) moves towards the first connecting head (62). An insertion hole (623) is provided in the first connecting head (62) for one end of the pipeline to be measured (3) to be inserted. A slot (632) is provided at the other end of the third piston (63) for one end of the pipeline to be measured to be inserted when the third piston (63) moves towards the first connecting head (62). An air inlet hole (613) is provided at the other end of the first connecting seat (61). An air guiding channel (633) is provided in the protruding portion (631) that penetrates the protruding portion (631) and the third piston (63) and is used to connect the air inlet hole (613) and the insertion hole (623). A ring-shaped first sealing cavity (65) is formed between the third sealing structure and the fourth sealing structure. A first air inlet hole (614) is provided in the first connecting seat (61). One end of the first air inlet hole (614) is communicated with the first sealing cavity (65). The other end of the first air inlet hole (614) forms a first air inlet (615). When compressed air enters the first air inlet (615), the third piston (63) is used to move towards the first connecting head (62) and squeeze the seal ring group (64) so that the seal ring group (64) deforms and is tightened against the inner wall of the first connecting head (62) and the outer wall of the pipeline to be measured (3). The inlet pressure of the first air inlet (615) is greater than the inlet pressure of the air inlet hole (613). The air inlet hole (613) in one of the outer wrapping type pipeline end sealing joints (6) in each pair of pipeline end sealing connection devices is blocked by a plug. The air inlet holes (613) in the other outer wrapping type pipeline end sealing joints (6) in each pair of pipeline end sealing connection devices are all connected to the first air outlet channel (212) in the corresponding differential pressure detection combined isolation valve (2).; 8. The pipeline airtightness detection device according to claim 7, characterized in that, An annular rib (634) is provided on the end face of the other end of the third piston (63), and the annular rib (634) is used to abut against and squeeze the sealing ring group (64); a support ring (66) made of a metal material and through which one end of the pipeline to be measured passes is embedded between the inner bottom of the first annular step (622) and the sealing ring group (64). One side of the support ring (66) abuts against the inner bottom of the first annular step (622), and the other side of the support ring (66) abuts against the sealing ring group (64). The support ring (66) is used to support the sealing ring group (64); the sealing ring group (64) includes a plurality of coaxially arranged second sealing rings (641), and the plurality of second sealing rings (641) are all embedded in the first annular step (622), and every two adjacent second sealing rings (641) abut against each other; the third sealing structure includes a third sealing ring (67). A second annular groove (635) is provided on the outer wall of the third piston (63), and the third sealing ring (67) is embedded in the second annular groove (635). The third sealing ring (67) is in close contact and sealed with the inner walls of the second annular groove (635) and the sliding cavity (611); a fifth vent hole (616) is provided on the side wall of the first connector (61), and the fifth vent hole (616) is used to communicate with the sliding cavity (611) located between the third sealing ring (67) and the first connection head (62); the fourth sealing structure includes a fourth sealing ring (68) and a fifth sealing ring (69). A third annular groove (636) and a fourth annular groove (637) are provided on the outer wall of the protruding portion (631). The third annular groove (636) and the fourth annular groove (637) are distributed along the axial direction of the protruding portion (631). The fourth sealing ring (68) and the fifth sealing ring (69) are respectively embedded in the third annular groove (636) and the fourth annular groove (637). The fourth sealing ring (68) is in close contact and sealed with the inner walls of the third annular groove (636) and the concave cavity (612), and the fifth sealing ring (69) is in close contact and sealed with the inner walls of the fourth annular groove (637) and the concave cavity (612); a second annular groove (638) is provided on the outer wall of the protruding portion (631) between the third annular groove (636) and the fourth annular groove (637). A sixth vent hole (617) is provided on the side wall of the first connector (61), and the sixth vent hole (617) is used to communicate with the second annular groove (638);A plurality of arc-shaped holes (624) evenly distributed in the circumferential direction are provided in the annular convex edge (621). Threaded holes (618) corresponding to each of the arc-shaped holes (624) are provided at one end of the first connecting seat (61). A small-diameter portion (6241) is provided at one end of each of the arc-shaped holes (624), and a large-diameter portion (6242) is provided at the other end of each of the arc-shaped holes (624). The first connector (62) is fixed to the first connecting seat (61) by bolts passing through the small-diameter portions (6241) and threadedly connected to the threaded holes (618). The inner diameter of each of the small-diameter portions (6241) is greater than the outer diameter of the screw portion of the bolt and less than the outer diameter of the head of the bolt. The inner diameter of each of the large-diameter portions (6242) is greater than the outer diameter of the head of the bolt. An annular tapered surface (6231) is provided on the inner wall of the socket (623) at the end away from the first annular step (622). The annular tapered surface (6231) is used for guiding the cooperation with the end of the pipeline to be measured (3) so that the end of the pipeline to be measured (3) can be inserted into the socket (623) and pass through the socket (623).; 9. The pipeline airtightness detection device according to claim 6, characterized in that, The internal expansion type pipe end sealing joint (7) includes a second connecting seat (71), a second connector (72), a sliding sleeve (73) and a third sealing ring (74); a seventh ventilation hole (711) is provided in the second connecting seat (71), an eighth ventilation hole (721) is coaxially provided in the second connector (72), one end of the second connector (72) is inserted into the second connecting seat (71) and fixed to the second connecting seat (71), a fifth sealing structure is provided between one end of the second connector (72) and the second connecting seat (71), the other end of the second connector (72) is for inserting into one end of the pipeline to be measured (3), one end of the seventh ventilation hole (711) is communicated with one end of the eighth ventilation hole (721), and the other end of the seventh ventilation hole (711) forms an inflation port (712); a second annular step (722) is provided on the outer wall of the other end of the second connector (72), the third sealing ring (74) is sleeved outside the other end of the second connector (72) and abuts against the second annular step (722); one end of the sliding sleeve (73) is slidably sleeved outside the second connector (72) and a sixth sealing structure is provided between the sliding sleeve (73) and the second connector (72), the other end of the sliding sleeve (73) is slidably sleeved outside the second connecting seat (71) and a seventh sealing structure is provided between the sliding sleeve (73) and the second connecting seat (71); the fifth sealing structure, the sixth sealing structure and the seventh sealing structure enclose an annular second sealing cavity (75), a second air inlet hole (713) is provided in the second connecting seat (71), one end of the second air inlet hole (713) is communicated with the second sealing cavity (75), and the other end of the second air inlet hole (713) forms a second air inlet (714). When compressed air enters through the second air inlet (714), one end of the sliding sleeve (73) is for moving towards one side of the third sealing ring (74) and extruding the third sealing ring (74) so that the third sealing ring (74) deforms and expands tightly against the outer wall of the second connector (72) and the inner wall of the pipeline to be measured (3); the inlet pressure of the second air inlet (714) is greater than the inlet pressure of the inflation port (712). The inflation port (712) in one of the internal expansion type pipe end sealing joints (7) in each pair of pipe end sealing connection devices is blocked by a plug, and the inflation ports (712) in the other internal expansion type pipe end sealing joints (7) in each pair of pipe end sealing connection devices are all connected to the first air outlet channel (212) in the corresponding differential pressure detection combined isolation valve (2).

10. The pipeline airtightness detection device according to claim 9, characterized in that, One end of the second connector (72) is coaxially provided with a threaded joint (723) whose outer diameter is smaller than that of the second connector (72). An internal thread (715) is provided on the inner wall of the second connector seat (71), and the threaded joint (723) is threadedly connected to the internal thread (715). A countersunk head (724) in the shape of a regular hexagon is provided on the inner wall of the other end of the second connector (72). An annular chamfer surface (725) is provided on the outer wall of the other end of the second connector (72) for cooperating with the inner wall of the pipeline to be measured (3) for guiding so that the other end of the second connector (72) can be inserted into the pipeline to be measured (3). The fifth sealing structure includes a sixth sealing ring (76). A fifth annular groove (726) is provided on the outer wall of one end of the second connector (72). The sixth sealing ring (76) is fitted in the fifth annular groove (726), and the sixth sealing ring (76) is in close contact and sealed with both the fifth annular groove (726) and the second connector seat (71). The sixth sealing structure includes a seventh sealing ring (77). A sixth annular groove (731) is provided on the inner wall of one end of the sliding sleeve (73). The seventh sealing ring (77) is fitted in the sixth annular groove (731), and the seventh sealing ring (77) is in close contact and sealed with both the sixth annular groove (731) and the outer wall of the second connector (72). The seventh sealing structure includes an eighth sealing ring (78). A seventh annular groove (716) is provided on the outer wall of the second connector seat (71). The eighth sealing ring (78) is fitted in the seventh annular groove (716), and the eighth sealing ring (78) is in close contact and sealed with both the seventh annular groove (716) and the inner wall of the other end of the sliding sleeve (73). A push sleeve (79) made of a metal material is slidably sleeved on the outside of the second connector (72) between the third sealing ring (74) and the sliding sleeve (73). One end of the push sleeve (79) is used to abut against the third sealing ring (74), and the other end of the push sleeve (79) is used to abut against one end of the sliding sleeve (73).

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