A pressure testing fixture and method for a support casing

Abstract

A pressure test fixture and a pressure test method for a support casing. The fixture includes a base, a top cover plate, an annular cover plate and a plug assembly; a first fastening structure is provided between the base and the top cover plate, and a second fastening structure is provided between the base and the annular cover plate; a hollow cylinder with both ends open is arranged in the inner hole of the annular cover plate; a third rubber ring is arranged on the lower surface of the annular cover plate; a first rubber ring and a second rubber ring are arranged on the upper surface of the base; the top cover plate has a lower-end open inner cavity, and a fourth rubber ring is arranged on the bottom wall of the inner cavity for sealing the top end surface of the inner casing; the top of the hollow cylinder is inserted into the inner cavity of the top cover plate, and a fifth rubber ring is arranged between the outer cylindrical surface of the hollow cylinder and the inner wall of the top cover plate; air connection nozzles are respectively arranged on the hollow cylinder and the top cover plate; the plug assembly is used for plugging the orifice of the transverse hole. The inner cavity and the support plate cavity of the support casing can be pressure-tested separately, which is convenient for quickly detecting the position of the weld defect.

Description

Technical Field

[0001] The present invention relates to the technical field of sealing performance testing for aero-engine components, and particularly to a pressure testing fixture and method for a support casing. Background Art

[0002] The part of the present invention that needs to be pressure tested is the support casing 100 of an aero-engine, and its structure is specifically as Figure 1 、 Figure 2 shown. The support casing 100 is composed of welding of ten support plates 101, an inner casing 103, an outer casing 104, etc. An outer ring of the inner casing support housing 105 is provided outside the inner casing 103. The part is a sheet-welded combined welded part with a large number of argon arc welds. After welding, an inner cavity and ten support plate cavities will be formed between the inner casing 103 and the support plates 101. There are transverse holes 102 for connecting parts of pipes on the support plates 101. The support casing 100 belongs to an engine load-bearing component, and after welding, higher performance requirements are imposed on the welds. It is necessary to perform a pressure test on the welds of these cavities to check the sealing performance of the welds.

[0003] Although the patent with the application number CN202011140309.2 discloses an airtightness detection fixture and method for an aero-engine support casing, the sealing detection of the S cavity and the inner cavity of the adapter pipe is realized through the lower-end surface sealing assembly, the upper-end surface sealing assembly, the pressing shoulder long bolt and the adapter pipe sealing assembly, and then the airtightness of the inner cavity of each support plate is detected by ventilating each support plate one by one.

[0004] However, in the support casing of the present invention that needs to be pressure tested, due to the existence of the inner cavity and the support plate cavities, as well as the presence of pipes on the support plates, it is difficult to perform the pressure test. The fixture of the above-mentioned prior art patent is not applicable to Figure 1 、 Figure 2 the support casing shown. Therefore, there is an urgent need to provide a pressure testing fixture and method for a support casing. Summary of the Invention

[0005] The main object of the present invention is to propose a pressure testing fixture and method for a support casing, aiming to solve the above technical problems.

[0006] To achieve the above object, on the one hand, the present invention provides a pressure testing fixture for a support casing, comprising a base, a top cover plate, an annular cover plate and a plug assembly; a first fastening structure is provided between the base and the top cover plate, and a second fastening structure is provided between the base and the annular cover plate; a hollow cylinder with both ends open is provided in the inner hole of the annular cover plate; a third rubber ring is provided on the lower surface of the annular cover plate for sealing the top surface of the outer ring of the inner casing support shell; a first rubber ring and a second rubber ring are provided on the upper surface of the base, the first rubber ring is used for sealing the lower end surface of the inner casing, and the second rubber ring is used for sealing the lower end surface of the outer ring of the inner casing support shell; the top cover plate has a lower-end open inner cavity, and a fourth rubber ring is provided on the bottom wall of the inner cavity for sealing the top surface of the inner casing; the top of the hollow cylinder is inserted into the inner cavity of the top cover plate, and a fifth rubber ring is provided between the outer cylindrical surface of the hollow cylinder and the inner wall of the top cover plate; air connection nozzles are provided on the hollow cylinder and the top cover plate respectively; the plug assembly is used for being installed in the transverse hole of the support plate of the support casing to block the orifice of the transverse hole located at the outer casing.

[0007] Preferably, two concentric annular grooves are provided on the upper surface of the base for inlaying the first rubber ring and the second rubber ring.

[0008] Preferably, the flatness of the bottom of the annular groove is 0.01 - 0.06 mm.

[0009] Preferably, the first fastening structure between the base and the top cover plate is a central shaft, the lower end of the central shaft is fixedly connected to the center of the base, and a connection plate is provided at the top of the central shaft and is connected to the top cover plate by bolts.

[0010] Preferably, a flange is provided at the lower end of the central shaft, and the flange is fixedly connected to the base by a positioning pin and screws.

[0011] Preferably, the second fastening structure between the base and the annular cover plate is multiple columns, the multiple columns are evenly distributed in a ring, the lower ends of the columns are fixedly connected to the base, and locking nuts are installed after the upper ends of the columns pass through the annular cover plate.

[0012] Preferably, an annular groove is provided on the outer cylindrical surface of the hollow cylinder for inlaying the fifth rubber ring; the fifth rubber ring protrudes 1 - 3 mm from the annular groove; the clearance between the outer peripheral surface of the hollow cylinder and the inner wall surface of the top cover plate is 0.02 - 0.1 mm; and the axial distance from the fifth rubber ring to the lower end surface of the inner cavity of the top cover plate is ≥ 3 mm.

[0013] Preferably, the inner diameter and outer diameter of the first rubber ring both exceed the lower end face of the inner casing by 5-10 mm; the inner diameter and outer diameter of the second rubber ring both exceed the lower end face of the outer ring of the inner casing support housing by 5-10 mm; the inner diameter and outer diameter of the third rubber ring both exceed the top face of the outer ring of the inner casing support housing by 5-10 mm; the inner diameter and outer diameter of the fourth rubber ring both exceed the top end face of the inner casing by 5-10 mm.

[0014] Preferably, the plugging component includes a pull rod and a sealing gasket; an outer plug is integrally formed at one end of the pull rod, an inner plug is provided at the other end, and the inner plug is threadedly connected to the pull rod; the sealing gasket is installed inside the outer plug; the rod diameter of the pull rod is smaller than the transverse hole diameter of the support plate of the support casing; a groove is formed on the end face of the inner plug in contact with the inside of the inner casing, and the transverse hole orifice inside the inner casing is not sealed during assembly.

[0015] On the other hand, the present invention also provides a pressure testing method for a support casing, using the above-mentioned pressure testing fixture, including the following steps:

[0016] Step S1: Install the plugging component in the transverse hole of the support plate of the support casing to block the transverse hole orifice at the outer casing.

[0017] Step S2: Install the support casing into the base so that the lower end face of the inner casing and the lower end face of the outer ring of the inner casing support housing are respectively in contact with the first rubber ring and the second rubber ring.

[0018] Step S3: Place the annular cover plate on the top of the outer ring of the inner casing support housing of the support casing, connect and lock it to the base through the second fastening structure, and make the third rubber ring fit on the top face of the outer ring of the inner casing support housing.

[0019] Step S4: Buckle the top cover plate on the hollow cylinder body, make the fourth rubber ring fit on the top end face of the inner casing, and connect and lock the top cover plate to the base through the first fastening structure.

[0020] Step S5: Put the clamped support casing together with the pressure testing fixture into the water tank, connect a trachea to the air connection nozzle on the hollow cylinder body and ventilate, the ventilation pressure is 0.2-0.3 Mpa, keep it for 20 min, and check if there are any bubbles emerging.

[0021] Step S6: After taking out the clamped support casing together with the pressure testing fixture, loosen the annular cover plate to release the seal of the third rubber ring, then put the support casing together with the pressure testing fixture into the water tank, connect a trachea to the air connection nozzle on the top cover plate and ventilate, the ventilation pressure is 0.2-0.3 Mpa, keep it for 20 min, and check if there are any bubbles emerging.

[0022] Step S7: After the pressure testing is completed, take out and disassemble the parts.

[0023] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0024] (1) By using the pressing fixture provided by the present invention, the quick clamping and positioning machining of the support casing can be carried out, greatly shortening the machining cycle of the parts;

[0025] (2) By using the pressing fixture and the pressing method provided by the present invention, the inner cavity and the support plate cavity of the support casing can be pressed separately, which is convenient for quickly detecting the position of the weld defect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0027] Figure 1 It is the top view of the support casing that needs to be subjected to the pressing test of the present invention;

[0028] Figure 2 It is Figure 1 the sectional view along AC-AC in

[0029] Figure 3 It is the structural schematic diagram when the support casing is installed on the pressing fixture provided by the present invention;

[0030] Figure 4 It is the structural schematic diagram when the plug assembly in the present invention is installed on the support casing;

[0031] Figure 5 It is the structural schematic diagram of the plug assembly in the present invention.

[0032] Explanation of the reference numerals in the drawings: 1, base; 2, top cover plate; 3, annular cover plate; 4, first rubber ring; 5, second rubber ring; 6, third rubber ring; 7, fourth rubber ring; 8, fifth rubber ring; 9, plug assembly; 10, column; 11, central axis; 12, hollow cylinder; 13, annular groove; 14, air connection nozzle; 15, pull rod; 16, sealing gasket; 17, outer plug; 18, inner plug; 100, support casing; 101, support plate; 102, transverse hole; 103, inner casing; 104, outer casing; 105, outer ring of the inner casing support shell. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0034] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0035] In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "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 is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0036] Combined with Figure 1 、 Figure 2 As shown, it is a structural schematic diagram of the support casing 100 that needs to be subjected to a pressure test in the present invention. The support casing 100 is welded and composed of ten support plates 101, an inner casing 103, an outer casing 104, etc. An outer ring 105 of the inner casing support housing is arranged outside the inner casing 103. The part belongs to a sheet metal welding combined welded part, and there are a large number of argon arc welds. After welding, an inner cavity and ten support plate cavities will be formed between the inner casing 103 and the support plates 101. There are transverse holes 102 for connecting parts of pipes on the support plates 101. The support casing 100 belongs to an engine load-bearing component. After welding, the performance requirements for the welds are relatively high, and the pressure test needs to be carried out on the welds of these cavities to check the sealing performance of the welds.

[0037] Combined with Figures 3 to 5As shown, a pressure testing fixture for a support casing includes a base 1, a top cover plate 2, an annular cover plate 3, and a plug assembly 9. A first fastening structure is provided between the base 1 and the top cover plate 2, and a second fastening structure is provided between the base 1 and the annular cover plate 3. A hollow cylinder 12 with open ends at both ends is provided in the inner hole of the annular cover plate 3. A third rubber ring 6 is provided on the lower surface of the annular cover plate 3 for sealing the top surface of the outer ring 105 of the inner casing support shell. A first rubber ring 4 and a second rubber ring 5 are provided on the upper surface of the base 1. The first rubber ring 4 is used for sealing the lower end surface of the inner casing, and the second rubber ring 5 is used for sealing the lower end surface of the outer ring 105 of the inner casing support shell. The top cover plate 2 has a lower-end open inner cavity, and a fourth rubber ring 7 is provided on the bottom wall of the inner cavity for sealing the top end surface of the inner casing 103. The top of the hollow cylinder 12 is inserted into the inner cavity of the top cover plate 2, and a fifth rubber ring 8 is provided between the outer cylindrical surface of the hollow cylinder 12 and the inner wall of the top cover plate 2. Air connection nozzles 14 are provided on the hollow cylinder 12 and the top cover plate 2 respectively. The plug assembly 9 is used for being installed in the transverse hole 102 of the support plate 101 of the support casing 100 for blocking the orifice of the transverse hole 102 at the outer casing 104. A plurality of lifting rings are provided on the top cover plate 2 to facilitate lifting after clamping the parts.

[0038] In this embodiment, two concentric annular grooves 13 are provided on the upper surface of the base 1 for embedding the first rubber ring 4 and the second rubber ring 5. By providing the annular grooves 13, it is convenient to install the first rubber ring 4 and the second rubber ring 5, so as to prevent the first rubber ring 4 and the second rubber ring 5 from shifting when being clamped and pressed, thereby ensuring the reliability of the seal. The flatness of the bottom of the annular groove 13 is 0.01 - 0.06 mm. By ensuring the flatness requirement, the flatness of the first rubber ring 4 and the second rubber ring 5 during pressing is ensured, and the sealing effect is guaranteed.

[0039] Combined with Figure 3 As shown, the first fastening structure between the base 1 and the top cover plate 2 is a central shaft 11. The lower end of the central shaft 11 is fixedly connected to the center of the base 1, and a connecting disk is provided at the top of the central shaft 11 and is connected to the top cover plate 2 by bolts. Specifically, a flange is provided at the lower end of the central shaft 11, and the flange is fixedly connected to the base 1 by a positioning pin and screws. By using the central shaft 11 to connect the base 1 and the top cover plate 2, the central shaft 11 can pass through the through hole of the inner casing 103 and the top cover plate 2, with a simple structure and convenient installation.

[0040] Combined with Figure 3As shown in the figure, the second fastening structure between the base 1 and the annular cover plate 3 is multiple columns 10. The multiple columns 10 are evenly distributed in a ring shape. The lower ends of the columns 10 are fixedly connected to the base 1, and locking nuts are installed after the upper ends of the columns 10 pass through the annular cover plate 3. Specifically, the number of columns 10 is six. By using the columns 10 for connection, the annular cover plate 3 can be evenly stressed, and the top surface of the outer ring 105 of the inner casing support shell can be better sealed.

[0041] Combined with Figure 3 As shown in the figure, an annular groove is provided on the outer cylindrical surface of the hollow cylinder 12 for inlaying the fifth rubber ring 8; the fifth rubber ring 8 protrudes 1 - 3 mm from the annular groove 1 - 3 mm; the fitting gap between the outer peripheral surface of the hollow cylinder 12 and the inner wall surface of the top cover plate 2 is 0.02 - 0.1 mm; and the axial distance of the fifth rubber ring 8 from the lower end face of the inner cavity of the top cover plate 2 is ≥ 3 mm. By providing the annular groove, it is convenient to install the fifth rubber ring 8, and at the same time, a limiting effect is formed on the fifth rubber ring 8 to prevent the fifth rubber ring 8 from shifting and falling off during pressure testing. At the same time, combined with the fitting gap between the outer peripheral surface of the hollow cylinder 12 and the inner wall surface of the top cover plate 2, the stability of the fifth rubber ring 8 during pressure testing is further ensured, and displacement and falling off are avoided. At the same time, by using the fitting gap between the outer peripheral surface of the hollow cylinder 12 and the inner wall surface of the top cover plate 2, when the top cover plate 2 is fixed, it can play a positioning role on the hollow cylinder 12, and then position the annular cover plate 3 to ensure that the third rubber ring (6) is aligned with the top surface of the outer ring 105 of the inner casing support shell.

[0042] The inner diameter and outer diameter of the first rubber ring 4 both exceed the lower end face of the inner casing by 5 - 10 mm; the inner diameter and outer diameter of the second rubber ring 5 both exceed the lower end face of the outer ring 105 of the inner casing support shell by 5 - 10 mm; the inner diameter and outer diameter of the third rubber ring 6 both exceed the top surface of the outer ring 105 of the inner casing support shell by 5 - 10 mm; the inner diameter and outer diameter of the fourth rubber ring 7 both exceed the top end face of the inner casing by 5 - 10 mm. Through the above structure, the sealing effect of each rubber ring is ensured.

[0043] Combined with Figure 5 As shown in the figure, the plugging head assembly 9 includes a pull rod 15 and a sealing gasket 16; an outer plugging head 16 is integrally formed at one end of the pull rod 15, and an inner plugging head 17 is provided at the other end. The inner plugging head 17 is thread - connected to the pull rod 15; the sealing gasket 16 is installed inside the outer plugging head 16; the rod diameter of the pull rod 15 is smaller than the diameter of the transverse hole 102 of the support plate 101 of the support casing; a groove is provided on the end face of the inner plugging head 17 in contact with the inside of the inner casing. During assembly, the orifice of the transverse hole 102 inside the inner casing is not sealed, and air flow can enter the inside of the transverse hole 102 during pressure testing, so as to facilitate the pressure test of the inside of the transverse hole 102.

[0044] On the other hand, the present embodiment also provides a method for pressure testing a support casing. Using the above - mentioned pressure testing fixture, it includes the following steps:

[0045] Step S1: Install the plug component 9 in the transverse hole 102 of the support plate 101 of the support casing 100 to block the orifice of the transverse hole 102 at the outer casing 104;

[0046] Step S2: Install the support casing 100 into the base 1 so that the lower end surface of the inner casing 103 and the lower end surface of the outer ring 105 of the inner casing support housing are respectively in contact with the first rubber ring 4 and the second rubber ring 5;

[0047] Step S3: Place the annular cover plate 3 on the top of the outer ring 105 of the inner casing support housing of the support casing 100, connect and lock it to the base 1 through the second fastening structure, and make the third rubber ring 6 fit on the top surface of the outer ring 105 of the inner casing support housing;

[0048] Step S4: Snap the top cover plate 2 onto the hollow cylinder 12, make the fourth rubber ring 7 fit on the top end surface of the inner casing 103, and connect and lock the top cover plate 2 to the base 1 through the first fastening structure;

[0049] Step S5: Place the clamped support casing 100 together with the pressure test fixture into the water tank, connect a trachea to the air connection nozzle 14 on the hollow cylinder 2 and ventilate, with a ventilation pressure of 0.2 - 0.3 Mpa, hold for 20 min, and check if there are any bubbles emerging;

[0050] Step S6: After taking out the clamped support casing 100 together with the pressure test fixture, loosen the annular cover plate 3 to release the seal of the third rubber ring 6, then place the support casing 100 together with the pressure test fixture into the water tank, connect a trachea to the air connection nozzle 14 on the top cover plate 2 and ventilate, with a ventilation pressure of 0.2 - 0.3 Mpa, hold for 20 min, and check if there are any bubbles emerging;

[0051] Step S7: After the pressure test is completed, take out and disassemble the parts.

[0052] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the inventive concept of the present invention by using the content of the specification and drawings of the present invention, or any direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A method for pressure testing a support casing, using a pressure testing fixture comprising a base (1), a top cover plate (2), an annular cover plate (3), and a plug assembly (9), characterized in that: A first fastening structure is provided between the base (1) and the top cover plate (2), and a second fastening structure is provided between the base (1) and the annular cover plate (3); A hollow cylinder body (12) with both ends open is provided in the inner hole of the annular cover plate (3); a third rubber ring (6) is provided on the lower surface of the annular cover plate (3) for sealing the top surface of the outer ring (105) of the inner casing support of the internal machine case; A first rubber ring (4) and a second rubber ring (5) are provided on the upper surface of the base (1). The first rubber ring (4) is used for sealing the lower end surface of the inner casing, and the second rubber ring (5) is used for sealing the lower end surface of the outer ring (105) of the inner casing support of the internal machine case; The top cover plate (2) has an inner cavity with an open lower end, and a fourth rubber ring (7) is provided on the bottom wall of the inner cavity for sealing the top end surface of the inner casing (103); The top of the hollow cylinder body (12) is inserted into the inner cavity of the top cover plate (2), and a fifth rubber ring (8) is provided between the outer cylindrical surface of the hollow cylinder body (12) and the inner wall of the top cover plate (2); air nozzles (14) are respectively provided on the hollow cylinder body (12) and the top cover plate (2); The plugging head assembly (9) is used for being installed in the transverse hole (102) of the support plate (101) of the support casing (100) to plug the orifice of the transverse hole (102) located at the outer casing (104); The method includes the following steps: Step S1: Install the plugging head assembly (9) in the transverse hole (102) of the support plate (101) of the support casing (100) to plug the orifice of the transverse hole (102) located at the outer casing (104); Step S2: Install the support casing (100) into the base (1) so that the lower end surface of the inner casing (103) and the lower end surface of the outer ring (105) of the inner casing support are respectively in contact with the first rubber ring (4) and the second rubber ring (5); Step S3: Place the annular cover plate (3) on the top of the outer ring (105) of the inner casing support of the support casing (100), connect and lock it to the base (1) through the second fastening structure, and make the third rubber ring (6) fit on the top surface of the outer ring (105) of the inner casing support; Step S4: Buckle the top cover plate (2) on the hollow cylinder body (12), make the fourth rubber ring (7) fit on the top end surface of the inner casing (103), and connect and lock the top cover plate (2) to the base (1) through the first fastening structure; Step S5: Put the clamped support casing (100) together with the pressure testing fixture into the water tank, connect a trachea to the air nozzle (14) on the hollow cylinder body (12) and ventilate, with the ventilation pressure of 0.2 - 0.3 Mpa, hold for 20 min, and check whether there are any bubbles emerging; Step S6: After taking out the clamped support casing (100) together with the pressure testing fixture, loosen the annular cover plate (3) to release the seal of the third rubber ring (6), then put the support casing (100) together with the pressure testing fixture into the water tank, connect a trachea to the air nozzle (14) on the top cover plate (2) and ventilate, with the ventilation pressure of 0.2 - 0.3 Mpa, hold for 20 min, and check whether there are any bubbles emerging; Step S7: After the pressure test is completed, remove and disassemble the parts.

2. The pressure test method for a support casing according to claim 1, characterized in that On the upper surface of the base (1), there are two concentric annular grooves (13) for inlaying the first rubber ring (4) and the second rubber ring (5).

3. The pressure test method for a support casing according to claim 2, characterized in that, The flatness of the bottom surface of the annular groove (13) is 0.01 - 0.06 mm.

4. The pressure test method for a support casing according to claim 1, characterized in that, The first fastening structure between the base (1) and the top cover plate (2) is the central shaft (11). The lower end of the central shaft (11) is fixedly connected to the center of the base (1), and a connecting plate is provided at the top end of the central shaft (11) and is connected to the top cover plate (2) by bolts.

5. A method for pressure testing a support casing as claimed in claim 4, characterized in that, A flange is provided at the lower end of the central shaft (11), and the flange is fixedly connected to the base (1) by positioning pins and screws.

6. The pressure test method for a support casing according to claim 1, characterized in that The second fastening structure between the base (1) and the annular cover plate (3) is multiple columns (10). The multiple columns (10) are evenly distributed in a ring. The lower ends of the columns (10) are fixedly connected to the base (1), and locking nuts are installed after the upper ends of the columns (10) pass through the annular cover plate (3).

7. A method for pressure testing a support casing as claimed in claim 1, characterized in that An annular groove is provided on the outer cylindrical surface of the hollow cylinder (12) for inlaying the fifth rubber ring (8); the fifth rubber ring (8) protrudes 1 - 3 mm from the annular groove; the clearance between the outer peripheral surface of the hollow cylinder (12) and the inner wall surface of the top cover plate (2) is 0.02 - 0.1 mm; and the axial distance from the fifth rubber ring (8) to the lower end face of the inner cavity of the top cover plate (2) is ≥ 3 mm.

8. A method for pressurizing a support casing according to claim 1, characterized in that, The inner diameter and outer diameter of the first rubber ring (4) both exceed the lower end face of the inner casing by 5 - 10 mm; the inner diameter and outer diameter of the second rubber ring (5) both exceed the lower end face of the outer ring (105) of the inner casing support shell by 5 - 10 mm; the inner diameter and outer diameter of the third rubber ring (6) both exceed the top face of the outer ring (105) of the inner casing support shell by 5 - 10 mm; the inner diameter and outer diameter of the fourth rubber ring (7) both exceed the top end face of the inner casing by 5 - 10 mm.

9. The pressure test method for a support casing according to claim 1, characterized in that, The plug assembly (9) includes a pull rod (15) and a sealing gasket (16); an outer plug (17) is integrally formed at one end of the pull rod (15), and an inner plug (18) is provided at the other end. The inner plug (18) is threadedly connected to the pull rod (15); the sealing gasket (16) is installed inside the outer plug (17); the rod diameter of the pull rod (15) is smaller than the diameter of the transverse hole (102) of the support plate (101) of the support casing; a groove is provided on the end face of the inner plug (18) in contact with the inside of the inner casing, and the transverse hole (102) orifice inside the inner casing is not sealed during assembly.

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