External pressure airtightness detection device and method for sealed components

Abstract

The present invention discloses a closed component external pressure type airtightness detection device and method, comprising a fixed plate; a bracket is provided on one side end of the fixed plate, and a gas tank body is provided on the other side end; a hand-turned valve and a gas distribution seat are provided on the upper end of the bracket; the hand-turned valve has a first interface, a second interface, a third interface and a fourth interface on four sides respectively; a T-shaped through hole is provided in the gas distribution seat, the upper end outlet is threadedly connected with a pressure gauge, the left side outlet is connected to the second interface of the hand-turned valve through a pipeline, the right side outlet is connected to the gas tank body through a pipeline and the right side outlet is connected to the inside of the gas tank body; a withdrawal nut is provided on the outer side of the upper end of the gas tank body; a screw is provided on the withdrawal nut; a gas cap is provided on the upper end of the withdrawal nut; a handle nut is threadedly connected to each screw and the handle nut is tightly pressed on the gas cap. The closed component external pressure type airtightness detection device and method provided by the present invention separately designs the gas cap sealing part and the transmission part, greatly reduces the weight of the gas cap, and makes the operation easy.

Description

Technical Field

[0001] The present invention relates to an airtightness detection device, and in particular to an airtightness detection device and method for an airtight component with external pressure. Background Art

[0002] Usually, when testing the air tightness of a sealed component, the workpiece is placed in a sealed container, compressed gas is filled into the container, and the pressure change in the container is observed to determine whether the workpiece has taken in air to test the air tightness of the sealed component. In general, the detection system is equipped with an intake valve and an exhaust valve to control the intake and exhaust of the test pipeline, but the leakage nodes increase and are relatively messy. The device consists of two major parts, the gas cap and the tank body, which are connected by threads. The gas cap includes two parts: sealing and screwing. When the workpiece is large and the test pressure is high, the gas cap needs to be completely unscrewed from the gas tank body each time the workpiece is taken out, and the entire gas cap is high and heavy; and each time the box cover is closed, it takes a long time to screw in and align the threads, which is inefficient and time-consuming and labor-intensive to operate; at the same time, it is necessary to use the structure of the workpiece itself for sealing, which may cause secondary damage to the workpiece and fail to better guarantee product quality. Summary of the invention

[0003] In view of this, the present invention proposes an external pressure airtight detection device and method for a closed component. In view of the defects existing in the original technology, the air inlet valve and the exhaust valve are combined into a hand-turned valve to reduce the leakage points and make the operation convenient; the bulky gas cap is separated into a sealing part and a transmission part. The transmission part is specially designed as a material withdrawal nut, which is always connected to the gas tank body through a thread during the transmission process, and the sealing part is the gas cap; when removing the parts, it is only necessary to remove the gas cap, so that the operation is light and fast, and the detection efficiency is high.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A closed component external pressure airtight detection device and method, comprising a fixed plate; a bracket is provided on one side end of the fixed plate, and a gas tank body is provided on the other side end; a hand-turned valve and a gas distribution seat are provided on the upper end of the bracket; the hand-turned valve is a manually controlled direct-acting, four-port, three-position center-sealed valve, and the four sides of the hand-turned valve are respectively provided with a first interface, a second interface, a third interface and a fourth interface; the manual valve is provided with a threaded two-way quick-change joint for controlling the opening and closing of the four interfaces, and the threaded two-way quick-change joint can be rotated to three gears. When the threaded two-way quick-change joint is rotated to the middle second gear, the first interface, the second interface, the third interface and the fourth interface are all in a closed state. When the threaded two-way quick-change joint is rotated to the first gear on the right side, the first interface is connected to the second interface, and the fourth interface is connected to the third interface. When rotated to the third gear on the left, the second interface is connected to the third interface, the first interface is connected to the fourth interface, and the fourth interface is installed with a plug; a T-shaped through hole is opened in the gas distribution seat, and the upper outlet is threadedly connected to a pressure gauge, the left outlet is connected to the second interface of the hand valve through a pipeline, the right outlet is connected to the gas tank body through a pipeline, and the right outlet is connected to the inside of the gas tank body; a withdrawal nut is threadedly connected to the outer side of the upper end of the gas tank body; a plurality of screws are fixed circumferentially on the withdrawal nut; a gas cap is provided on the upper end of the withdrawal nut, a plurality of slots are opened on the edge of the gas cap, and the plurality of slots are respectively provided for a plurality of screws to pass through, and the gas cap completely covers the upper end opening of the gas tank body; a handle nut is threadedly connected to each of the screws, and the handle nut is tightly crimped on the gas cap to press the gas cap and the withdrawal nut into one.

[0006] Preferably, the fixing plate is a rectangular steel plate; a circular hole is formed at the other side end of the fixing plate.

[0007] Preferably, the gas tank body is a hollow cylinder, which is welded by an upper circular tube and a lower circular cover; the upper circular tube of the gas tank body is provided with radial grooves, a cylindrical guide section, a conductive thread section and a limit shoulder from top to bottom in sequence; an O-ring is embedded in the radial groove, the gas cover is in contact with the O-ring and the O-ring is compressed and deformed; the withdrawal nut is in contact with the upper end surface of the cylindrical guide section; a small plane is partially milled on the side surface of the conductive thread section, and a sealing conical pipe thread through hole is vertically provided on the small plane; the convex circular ring on the outer bottom wall of the limit shoulder is matched in the circular hole of the fixed plate, and the inner bottom wall of the limit shoulder is provided with a cross groove; the workpiece is placed in the position corresponding to the cross groove in the gas tank body.

[0008] Preferably, the withdrawal nut is an annular part; two small planes are milled symmetrically on both sides of the circumferential surface of the withdrawal nut compared to the central axis, and two threaded holes are vertically opened on the two small planes, and handles are threadedly connected to the two threaded holes; three countersunk holes are circumferentially opened on the upper and lower surfaces of the withdrawal nut, and three screws are respectively welded in the three countersunk holes; the inner hole of the withdrawal nut is a stepped hole, the lower section hole is a threaded hole, and the upper section is a smooth hole, and the withdrawal nut is threadedly connected to the outside of the cylindrical guide section of the gas tank body through the lower section threaded hole.

[0009] Preferably, the gas cover is in the shape of a cover; three semi-waist-shaped slots are provided on the edge of the gas cover, the gas cover is arranged on the upper end of the withdrawal nut and three screws are respectively passed through the three semi-waist-shaped slots; a handle is welded on the middle part of the upper surface of the gas cover.

[0010] Preferably, the gas distribution seat is convex-shaped; the upper end opening of the gas distribution seat is an internally threaded through hole, and the left and right outlets are sealed conical tube threaded through holes; a sealing gasket is embedded between the pressure gauge and the bottom end surface of the upper end opening; the left and right sealed conical tube threaded through holes are respectively threadedly connected with threaded straight-through quick-change joints, the second interface of the hand-turned valve is internally threadedly connected with a threaded straight-through quick-change joint, a hose is provided between the left-side threaded straight-through quick-change joint of the gas distribution seat and the threaded straight-through quick-change joint of the hand-turned valve, the sealing conical tube threaded through hole of the gas tank body is internally threadedly connected with a threaded straight-through quick-change joint, and a hose is provided between the right-side threaded straight-through quick-change joint of the gas distribution seat and the threaded straight-through quick-change joint of the gas tank body.

[0011] Preferably, the bracket is in an I-shape; a hand valve and a gas distribution seat are threadedly connected on the top surface of the bracket, and the bottom surface of the bracket is threadedly connected to a fixed plate.

[0012] The present invention also provides a method for detecting a closed component external pressure airtightness detection device, comprising the following steps:

[0013] S1: During the test, first put the workpiece into the gas tank body, hold the handle and rotate the withdrawal nut counterclockwise to make its upper surface exceed the O-ring, hold the handle to align the slot of the gas cover ear with the connecting screw on the withdrawal nut to cover the gas tank body, and then screw the three handle nuts into the connecting screws to press and fix the gas cover and the withdrawal nut together; then hold the handle and rotate the withdrawal nut clockwise, and the gas cover and the withdrawal nut will go down together until the lower surface touches the shoulder of the gas tank body; at the same time, the gas cover goes down and compresses the O-ring to seal the gas cover and the gas tank body;

[0014] S2: After assembly, turn the handle of the hand-turn valve to the first position. There are four interfaces on the four sides of the hand-turn valve, namely the first interface P, the fourth interface A, the second interface B, and the third interface R. The compressed gas from the gas source passes through the P port → B port of the hand-turn valve, and at the same time, the A port and the R port are connected, and then go to the gas distribution seat. The inside of the gas distribution seat is a three-way pipeline. Part of the gas enters the pressure gauge and displays the pipeline pressure; the other part of the gas enters the gas tank through the hose, so that the gas fills the gas tank, and the workpiece is evenly subjected to external pressure until the pressure on the pressure gauge reaches the test pressure; after stabilizing the pressure, turn the handle of the hand-turn valve to the second position, close the test pipeline and start timing; observe the pressure change of the test system, and judge whether the workpiece is leaking by the size of the pressure change;

[0015] S3: After the test, turn the handle of the hand-turn valve to the third gear, and the compressed gas from the gas source will flow through the P port of the hand-turn valve to the A port. Since the A port is equipped with a plug, the system pipeline is closed; at the same time, the B port and the R port are connected, the gas in the test pipeline is discharged, and the pressure is released;

[0016] S4: Next, hold the handle and rotate the withdrawal nut counterclockwise. The air cap goes up with the withdrawal nut. After rotating for about the set number of circles, its upper surface exceeds the O-ring, and the air cap is pushed out of the gas tank body. It is no longer subject to the expansion force of the O-ring and can be easily taken out. Because the inner diameter of the withdrawal nut is larger than the outer diameter of the O-ring, the withdrawal nut is not subject to the expansion force of the O-ring during the up and down movement, making it easy to rotate the withdrawal nut. Unscrew the handle nut, take out the workpiece, and complete the entire test. Then rotate the hand valve handle to the second gear to close all test pipelines.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The whole device is novel and ingenious in design. By integrating the intake valve and the exhaust valve into a hand-operated valve, it reduces the leakage points and makes operation easier.

[0019] (2) The device separates the gas cap sealing part from the transmission part, which greatly reduces the weight of the gas cap and makes it easy to operate; the withdrawal nut is always screwed to the gas tank body during the transmission process, which saves a lot of alignment and screwing time, shortens the transmission stroke, saves time and effort, and has high detection efficiency;

[0020] (3) The inner hole of the designed withdrawal nut is larger than the outer diameter of the O-ring so that it is not affected by the expansion force of the O-ring during the transmission process, making it easier to rotate and saving effort;

[0021] (4) The external pressure detection method does not need to use the structure of the workpiece itself for sealing, thus avoiding secondary damage to the workpiece and better ensuring product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1It is the overall front view of the present invention;

[0023] Figure 2 It is an overall top view of the present invention;

[0024] Figure 3 It is a front view of the gas tank body of the present invention;

[0025] Figure 4 A top view of the gas tank body of the present invention;

[0026] Figure 5 It is a front cross-sectional view of the gas distribution seat of the present invention.

[0027] Figure 6 It is a left side view of the gas distribution seat of the present invention;

[0028] Figure 7 A top view of the bracket of the present invention;

[0029] Figure 8 A side view of the bracket of the present invention;

[0030] Fig. 9 It is a front cross-sectional view of the withdrawal nut of the present invention;

[0031] Fig.10 It is a top view of the withdrawal nut of the present invention.

[0032] Fig.11 It is a front cross-sectional view of the air cover of the present invention;

[0033] Fig.12 A top view of the air cover of the present invention;

[0034] Fig.13 It is a schematic diagram of the graphic symbol of the hand-turn valve of the present invention;

[0035] Fig.14 It is a top view of the hand-operated valve of the present invention.

[0036] In the figure: 1. fixing plate; 2. gas tank body; 201. radial groove; 202. cylindrical guide section; 203. conductive thread section; 204. limit shoulder; 205. cross groove; 3. large bolt; 4. large washer; 5. threaded straight-through quick-change connector; 6. hose; 7. small bolt; 8. small washer; 9. gas distribution seat; 10. bracket; 11. threaded two-way quick-change connector; 12. plug; 13. screw; 14. hand valve; 15. pressure gauge; 16. sealing gasket; 17. withdrawal nut; 18. connecting screw; 19. handle nut; 20. O-ring; 21. gas cover; 22. handle; 23. handle. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0038] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0039] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] Example:

[0041] like Figure 1-14 As shown, the present invention provides an external pressure airtightness detection device and method for a closed component, which mainly consists of a fixing plate 1, a gas tank body 2, a large bolt 3, a large gasket 4, a threaded straight-through quick-change joint 5, a PU hose 6, a small bolt 7, a small gasket 8, a gas distribution seat 9, a bracket 10, an L-shaped threaded two-way quick-change joint 11, a plug 12, a screw 13, a hand valve 14, a pressure gauge 15, a sealing gasket 16, a withdrawal nut 17, a connecting screw 18, a handle nut 19, an O-ring 20, a gas cover 21, a handle 22 and a handle 23.

[0042] refer to Figure 1 , Figure 2The fixing plate 1 is a rectangular steel plate with a round hole at one end. The hand-turned valve 14 and the gas distribution seat 9 are installed on the bracket 10 by screws 13, and the bracket 10 is then installed on the fixing plate 1 by four small bolts 7 and small washers 8. The short axis at the bottom of the gas tank body 2 is inserted into the round hole of the fixing plate 1 for correction, and is fixed to the fixing plate 1 by bolts through four semi-waist grooves evenly distributed along the radial direction of the lower convex edge of the gas tank body 2. The gas source, the hand-turned valve 14, the gas distribution seat 9 and the gas tank body 2 are connected together by a hose 6 and a threaded straight-through quick-change connector 5. The pressure gauge 15 is installed on the gas distribution seat 9 by a threaded connection, and the pressure gauge 15 and the gas distribution seat 9 are sealed by a compression seal 16.

[0043] The withdrawal nut 17 is connected to the upper section of the gas tank body 2 by threading, and three connecting screws 18 are welded in the countersunk holes evenly distributed in the withdrawal nut 17. The two opposite sides of the withdrawal nut 17 are milled flat, and the handle 23 is installed thereon by threading. The three radial convex ears on the gas cover 21 are milled with semi-waist-shaped grooves to be inserted into the connecting screws 18, and then the handle nut 19 is used to press it with the withdrawal nut 17, and at the same time, the O-ring 20 is compressed and deformed to play a sealing role. The handle 22 is welded on the gas cover 21.

[0044] refer to Figure 3 , Figure 4 The gas tank body 2 is a cylinder with a convex circular ring at the lower end, which is welded by a circular tube and a circular cover. From top to bottom, the upper circular tube of the gas tank body 2 is sequentially machined with a radial groove 201 of the O-ring 20, a cylindrical guide section 202, a conductive thread section 203 and a limit shoulder 204. A small plane is partially milled in the middle section of the conductive thread section 203 and a sealed conical tube threaded through hole is vertically machined. The diameter of the bottom circular cover is larger than the circular tube. A shallow large countersunk hole is machined on the upper surface of the circular cover, and the circular tube is inserted into it. The surrounding welding is dense and leak-free. A cross groove 205 is milled at the bottom of the countersunk hole to prevent the workpiece from being sucked after being placed in contact with the bottom surface. Four semi-waisted grooves are evenly milled on the peripheral circular ring, and bolts are passed through the slots to fix it on the fixed plate 1. The convex circular ring at the bottom end of the bottom limit shoulder 204 is inserted into the circular hole of the fixed plate 1 to play a positioning and guiding role.

[0045] refer to Figure 5 , Figure 6 The gas distribution seat 9 is a convex part with a T-shaped through hole in the middle, an internal thread at the outlet, sealed conical pipe threads on the left and right, a metric thread on the top, a cutter groove under the thread, and a small round hole below. The upper surface of the round hole is smooth, and the sealing gasket 16 is placed here. There are two screw countersunk holes on each side, and the gas distribution seat 9 is fixed to the bracket 10 with 4 screws through the countersunk holes.

[0046] refer to Figure 7 , Figure 8The bracket 10 is in the shape of a Chinese character "X", with two sets of threaded holes in the middle top, and the hand valve 14 and the gas distribution seat 9 are installed on it by screws. The left and right legs each have two round through holes, which are installed on the fixed plate 1 with four small bolts 7 and small washers 8.

[0047] refer to Fig. 9 , Fig.10 The withdrawing nut 17 is a ring-shaped part with two small planes milled symmetrically on the circumference. The vertical small plane has two threaded holes, and the handle 23 is installed here. There are three countersunk holes evenly distributed on the circumference of the vertical upper and lower surfaces, and the connecting screws 18 are inserted and fixed here by spot welding. The middle part of the upper surface is convex, and the surface is smooth and contacts the lower surface of the gas cover 21. The inner hole is a stepped hole, the larger hole below is a threaded hole, and the smaller hole above is a smooth hole. The threaded inner hole matches the external thread of the upper section of the gas tank body 2.

[0048] refer to Fig.11 , Fig.12 The gas cover 21 is a cover-shaped part with three ears, and the ears are milled with a half-waist-shaped slot. The connecting screw 18 on the withdrawal nut 17 passes through the hole and is connected to the handle nut 19. The handle 22 is welded in the center of the upper surface of the gas cover 21.

[0049] refer to Fig.13 , Fig.14 The hand-turn valve 14 is a manual direct-acting, four-port, three-position center-sealed valve. The valve base is square, with four interfaces on each side, namely, the first interface P, the fourth interface A, the second interface B, and the third interface R, and there are three gears. When the pipeline is not in use, the handle is placed in the second gear, and the four interfaces P, A, B, and R are all in a closed state. During the test, the handle is rotated to the first gear, and the P port → B port and the A port → R port are connected, and the gas source gas enters the gas tank body 2 from the P port through the B port. After the test, the handle is rotated to the third gear, and the B port → R port and the P port → A port are connected. Because the A port is equipped with a plug 12, the gas source gas is closed, and the test pipeline gas is discharged from the R port. When all the pipeline gas is discharged, the handle is rotated to the first gear again. There are four round holes at the four corners of the square valve seat, and the screws 13 pass through the holes to fix it on the bracket 10. The valve has light reversing rotation, good hand feel, and accurate positioning. The effective flow area is large and the pressure loss is small.

[0050] The present invention also provides a method for detecting a closed component external pressure airtightness detection device, comprising the following steps:

[0051] S1: During the test, first put the workpiece into the gas tank body 2, hold the handle 23 and rotate the withdrawal nut 17 counterclockwise to make its upper surface exceed the O-ring 20, hold the handle 22 and align the ear slot of the gas cap 21 with the connecting screw 18 on the withdrawal nut 17 to cover the gas tank body 2, then screw the three handle nuts 19 into the connecting screw 18 to press and fix the gas cap 21 and the withdrawal nut 17 together; then hold the handle 23 and rotate the withdrawal nut 17 clockwise, and the gas cap 21 and the withdrawal nut 17 go down together until the lower surface touches the shoulder of the gas tank body 2; at the same time, the gas cap 21 goes down and compresses the O-ring 20, so that the gas cap 21 and the gas tank body 2 are sealed;

[0052] S2: After the assembly is in place, the handle of the hand-turn valve 14 is rotated to the first gear, and the compressed gas from the gas source passes through the P port → B port of the hand-turn valve 14, and at the same time, the A port and the R port are connected, and then go to the gas distribution seat 9. The gas distribution seat 9 has a three-way pipeline inside. Part of the gas enters the pressure gauge and displays the pipeline pressure; the other part of the gas enters the gas tank body 2 through the hose, so that the gas fills the gas tank body 2 (the workpiece is evenly subjected to the external pressure) until the pressure gauge pressure reaches the test pressure; after the pressure is stabilized, the handle of the hand-turn valve 14 is rotated to the second gear, the test pipeline is closed and the timing is started; observe the pressure change of the test system, and judge whether the workpiece is leaking by the size of the pressure change;

[0053] S3: After the test, the handle of the hand-operated valve 14 is turned to the third gear, and the compressed gas from the gas source passes through the P port of the hand-operated valve 14 → the A port. Since the A port is equipped with a plug 12, the system pipeline is closed; at the same time, the B port and the R port are connected, the gas in the test pipeline is discharged, and the pressure is released;

[0054] S4: Next, hold the handle 23 and rotate the withdrawing nut 17 counterclockwise. The gas cap 21 moves upward together with the withdrawing nut 17. After rotating for about the set number of circles, its upper surface exceeds the O-ring 20, and the gas cap 21 is pushed out of the gas tank body 2 and is no longer subject to the expansion force of the O-ring, so it can be easily taken out. Because the inner hole diameter of the withdrawing nut 17 is larger than the outer diameter of the O-ring, the withdrawing nut 17 is not subject to the expansion force of the O-ring during the up and down movement, so that the withdrawing nut 17 can be easily rotated. Unscrew the handle nut 19, take out the workpiece, and complete the entire test. Then rotate the handle of the hand valve 14 to the second gear to close all test pipelines.

[0055] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A detection method for a closed component external pressure airtightness detection device, characterized in that: The detection device comprises a fixing plate (1); a bracket (10) is provided on one side end of the fixing plate (1), and a gas tank body (2) is provided on the other side end; a hand-operated valve (14) and a gas distribution seat (9) are provided on the upper end of the bracket (10); the hand-operated valve (14) is a manually controlled direct-acting, four-port, three-position center-sealed valve; the four sides of the hand-operated valve (14) respectively have a first interface, a second interface, a third interface and a fourth interface; the hand-operated valve (14) is provided with a threaded two-way quick-change joint (11) for controlling the opening and closing of the four interfaces; the threaded two-way quick-change joint (11) can be rotated to three gears; when the threaded two-way quick-change joint (11) is rotated to the middle second gear, the first interface, the second interface, the third interface and the fourth interface are all in a closed state; when the threaded two-way quick-change joint (11) is rotated to the first gear on the right side, the first interface is connected to the second interface, and the fourth interface is connected to the third interface; when the threaded two-way quick-change joint (11) is rotated to the third gear on the left side, the second interface is connected to the third interface. The interface is connected, the first interface is connected to the fourth interface, and the fourth interface is installed with a plug (12); a T-shaped through hole is opened in the gas distribution seat (9), the upper outlet is threadedly connected to a pressure gauge (15), the left outlet is connected to the second interface of the hand valve (14) through a pipeline, the right outlet is connected to the gas tank body (2) through a pipeline, and the right outlet is connected to the inside of the gas tank body (2); the upper outer side of the gas tank body (2) is threadedly connected to a withdrawal nut (17); the withdrawal nut (17) is fixed circumferentially A plurality of screws (13) are provided; a gas cover (21) is provided at the upper end of the withdrawal nut (17); a plurality of slots are provided at the edge of the gas cover (21) and the plurality of screws (13) are respectively passed through the plurality of slots; the gas cover (21) completely covers the upper end opening of the gas tank body (2); a handle nut (19) is threadedly connected to each of the screws (13), and the handle nut (19) is tightly pressed onto the gas cover (21) to press and fix the gas cover (21) and the withdrawal nut (17) into one body; The detection method comprises the following steps: S1: During the test, first place the workpiece into the gas tank body (2), hold the handle (23) and rotate the withdrawal nut (17) counterclockwise until its upper surface exceeds the O-ring (20), hold the handle (22) and align the ear slot of the gas cap (21) with the connecting screw (18) on the withdrawal nut (17) to cover the gas tank body (2), then screw (3) handle nuts (19) into the connecting screw (18) to press and fix the gas cap (21) and the withdrawal nut (17) together; then hold the handle (23) and rotate the withdrawal nut (17) clockwise, and the gas cap (21) and the withdrawal nut (17) move downward together until the lower surface touches the shoulder of the gas tank body (2); at the same time, the gas cap (21) moves downward to compress the O-ring (20), so that the gas cap (21) and the gas tank body (2) are sealed; S2: After the assembly is in place, the handle of the hand-turned valve (14) is rotated to the first gear position. There are four interfaces on the four sides of the hand-turned valve (14), namely the first interface P, the fourth interface A, the second interface B, and the third interface R. The compressed gas from the gas source passes through the P port → B port of the hand-turned valve (14), and the A port and the R port are connected, and then goes to the gas distribution seat (9). The inside of the gas distribution seat (9) is a three-way pipeline. Part of the gas enters the pressure gauge and displays the pipeline pressure; the other part of the gas enters the gas tank body (2) through the hose, so that the gas fills the gas tank body (2), and the workpiece is evenly subjected to the external pressure until the pressure displayed on the pressure gauge reaches the test pressure; after the pressure is stabilized, the handle of the hand-turned valve (14) is rotated to the second gear position, the test pipeline is closed and the timing is started; the pressure change of the test system is observed, and the size of the pressure change is used to determine whether the workpiece is leaking; S3: After the test, the handle of the hand-operated valve (14) is turned to the third gear, and the compressed gas from the gas source flows through the P port of the hand-operated valve (14) to the A port. Since the A port is equipped with a plug (12), the system pipeline is closed; at the same time, the B port and the R port are connected, the gas in the test pipeline is discharged, and the pressure is released; S4: Next, hold the handle (23) and rotate the withdrawal nut (17) counterclockwise. The gas cap (21) moves upward together with the withdrawal nut (17). After rotating the set number of times, the upper surface of the gas cap (21) exceeds the O-ring (20). The gas cap (21) is pushed out of the gas tank body (2) and is no longer subject to the expansion force of the O-ring. It can be easily removed. Because the inner diameter of the withdrawal nut (17) is larger than the outer diameter of the O-ring, the withdrawal nut (17) is not subject to the expansion force of the O-ring during the upward and downward movement, making it easy to rotate the withdrawal nut (17). Unscrew the handle nut (19), remove the workpiece, and complete the entire test. Then, rotate the handle of the hand valve (14) to the second gear position to close all test pipelines.

2. The detection method of the closed component external pressure type airtightness detection device according to claim 1 is characterized in that: The fixing plate (1) is a rectangular steel plate; a circular hole is provided at the other side end of the fixing plate (1).

3. The detection method of the closed component external pressure type airtightness detection device according to claim 2 is characterized in that: The gas tank body (2) is a hollow cylinder, which is formed by welding an upper circular tube and a lower circular cover; the upper circular tube of the gas tank body (2) is provided with a radial groove (201), a cylindrical guide section (202), a conductive thread section (203) and a limit shaft shoulder (204) in order from top to bottom; an O-type sealing ring (20) is embedded in the radial groove (201), the gas cover (21) is in contact with the O-type sealing ring (20), and the O-type sealing ring (20) is compressed and deformed. The withdrawing nut (17) is arranged in contact with the upper end surface of the cylindrical guide section (202); a small plane is partially milled on the side surface of the conductive thread section (203), and a sealing conical tube thread through hole is vertically opened on the small plane; the outer bottom wall convex ring of the limiting shaft shoulder (204) is matched and arranged in the circular hole of the fixing plate (1), and the inner bottom wall of the limiting shaft shoulder (204) is opened with a cross groove (205); the workpiece is placed in the gas tank body (2) at a position corresponding to the cross groove (205).

4. The detection method of the closed component external pressure type airtightness detection device according to claim 3 is characterized in that: The withdrawing nut (17) is an annular part; two small planes are milled symmetrically on both sides of the circumferential surface of the withdrawing nut (17) relative to the central axis, and two threaded holes are vertically opened on the two small planes, and handles (23) are threadedly connected in the two threaded holes; three countersunk holes are opened in the circumferential direction on the upper and lower surfaces of the withdrawing nut (17), and three screws (13) are respectively welded in the three countersunk holes; the inner hole of the withdrawing nut (17) is a stepped hole, the lower hole is a threaded hole, and the upper hole is a smooth hole, and the withdrawing nut (17) is threadedly connected to the outer side of the cylindrical guide section (202) of the gas tank body (2) through the lower threaded hole.

5. The detection method of the closed component external pressure type airtightness detection device according to claim 4 is characterized in that: The gas cover (21) is in the shape of a cover; three semi-waist-shaped slots are provided on the edge of the gas cover (21); the gas cover (21) is covered on the upper end of the withdrawal nut (17) and three screws (13) are respectively passed through the three semi-waist-shaped slots; a handle (22) is welded on the middle part of the upper surface of the gas cover (21).

6. The detection method of the closed component external pressure type airtightness detection device according to claim 5, characterized in that: The gas distribution seat (9) is convex; the upper end opening of the gas distribution seat (9) is an internal threaded through hole, and the left and right outlets are sealed conical tube threaded through holes; a sealing gasket (16) is embedded between the pressure gauge (15) and the bottom end surface of the upper end opening; the left and right sealed conical tube threaded through holes are respectively threadedly connected with threaded straight-through quick-change joints (5); the second interface of the hand-turned valve (14) is internally threadedly connected with a threaded straight-through quick-change joint (5); a hose (6) is provided between the left threaded straight-through quick-change joint (5) of the gas distribution seat (9) and the threaded straight-through quick-change joint (5) of the hand-turned valve (14); the sealed conical tube threaded through hole of the gas tank body (2) is internally threadedly connected with a threaded straight-through quick-change joint (5); and a hose (6) is provided between the right threaded straight-through quick-change joint (5) of the gas distribution seat (9) and the threaded straight-through quick-change joint (5) of the gas tank body (2).

7. The detection method of the closed component external pressure type airtightness detection device according to claim 6, characterized in that: The bracket (10) is in the shape of an "X"; a hand valve (14) and a gas distribution seat (9) are threadedly connected on the top surface of the bracket (10), and the bottom surface of the bracket (10) is threadedly connected to the fixing plate (1).

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