Back pressure type ultra-high pressure seal structure and method of using same

Abstract

The application discloses a back pressure type ultrahigh pressure sealing structure and a use method thereof. A center cover is arranged in a product shell, and is fixed on an end surface of the product by a bolt to form two radial seals, thereby realizing sealing of a large end of a high pressure cavity of the product. A mandrel sealing structure and a pressing ring are arranged on the opposite side of the center cover, the pressing ring is fixed with a small end of the product by the bolt, and a large nut is screwed on the mandrel, thereby realizing sealing of a small end of the high pressure cavity of the product. Then, the upper cover, an auxiliary O-shaped ring and an auxiliary blocking ring are arranged on a flange of an outer ring of the product by the bolt to form an auxiliary cavity on an upper end surface of the center cover. During use, the high pressure cavity and the auxiliary cavity are simultaneously pressurized, the stress of the center cover is quantitatively transmitted to the upper cover by adjusting the pressure of the auxiliary cavity, and the stress of the center cover under the pressure in the high pressure cavity is effectively reduced. The application is an ultrahigh pressure sealing structure which is reliable in sealing, simple in dismounting and capable of quantitatively transmitting force.

Description

TECHNICAL FIELD

[0001] The present application relates to a back pressure type ultra-high pressure sealing structure and a method for using the same, which is applied to liquid gas pressure test of aerospace products, in particular, sealing of shell type parts during high pressure and ultra-high pressure test, and belongs to the technical field of sealing. BACKGROUND

[0002] In addition to defects of the material itself, various defects will be generated in the manufacturing and use of metal parts. In order to examine the influence of defects on the safety of metal parts, the metal parts need to be subjected to pressure test after being manufactured. When some shell type parts are subjected to pressure test, sealing of the parts is essential. However, sometimes the sealing is limited by space or structure, and the threaded hole on the metal part is not strong enough to bear the entire stress generated during pressure test, so other places need to bear the stress generated during pressure test together. In order to not damage the threaded hole of the metal part and also achieve effective sealing, the currently adopted methods mainly include increasing the diameter of the threaded hole on the part, so as to use thicker bolts for connection, or changing the material of the metal part, so as to use a material with higher strength to achieve reliable sealing effect. However, both of the above methods change the product, resulting in unqualified or unsatisfactory product. SUMMARY

[0003] The present application aims to overcome the above-mentioned defects, and provide a back pressure type ultra-high pressure sealing structure and a method for using the same, which can avoid damaging the threaded hole of the metal part and also achieve reliable sealing without changing the material of the metal part.

[0004] The above-mentioned object of the present application is achieved by the following scheme:

[0005] The back pressure type ultra-high pressure sealing structure comprises a center plug, a nut, a pressure ring, an upper plug, an outer ring bolt and a large end bolt.

[0006] The center plug is welded by a flange and a mandrel, the center plug is inserted into a product shell, the flange is fixed to the product shell by the large end bolt, and the upper plug is located at the top end of the flange and is fixed to the outer ring bolt hole of the product shell by the outer ring bolt.

[0007] A high pressure cavity is formed between the center plug and the product shell, and two radial sealing structures are arranged between the flange and the product shell to achieve sealing of the large end of the high pressure cavity.

[0008] A mandrel sealing structure is arranged between the lower end of the mandrel and the product shell, the pressure ring is sleeved on the mandrel, the pressure ring is pressed against the mandrel sealing structure under the extrusion of the nut to achieve sealing of the small end of the high pressure cavity, and the pressure ring is fixed to the product shell by a plurality of bolts.

[0009] The upper plug has a step on the lower end face, and an auxiliary cavity is formed between the upper plug and the center plug after installation; an auxiliary cavity sealing structure is arranged between the outer circle of the upper plug step and the center plug; two through holes are formed on the upper plug, which are communicated with the auxiliary cavity, and the top end of the through hole is connected with external pipeline through a connector.

[0010] Preferably, two annular grooves are arranged on the flange, and a radial sealing structure is arranged in each annular groove, and each radial sealing structure is composed of a second O-ring and a second retainer.

[0011] Preferably, the mandrel sealing structure comprises a first retainer and two first O-rings, and the first retainer is located between the two first O-rings.

[0012] The mandrel is matched with the pressure ring, and the initial sealing is established by tightening the nut to press the first O-rings and the first retainer; as the pressure gradually increases, the specific pressure of the upper first O-ring of the mandrel increases, and the first O-ring moves downward to press the first retainer and further press the lower first O-ring, so as to realize the sealing of the small end of the high-pressure cavity.

[0013] Preferably, the auxiliary cavity sealing structure is realized by an auxiliary retainer and an auxiliary O-ring.

[0014] Preferably, the step depth of the lower end face of the upper plug is 1-3mm.

[0015] Preferably, one connector of the upper plug is used to fill a certain pressure liquid into the auxiliary cavity, and the other connector is used to exhaust the air in the auxiliary cavity, so that the liquid can be filled more easily.

[0016] Preferably, the upper plug and the center plug belong to non-rigid contact, and by reasonably adjusting the pressure between the high-pressure cavity and the auxiliary cavity, the force borne by the large end threaded hole of the high-pressure cavity can be quantitatively transmitted to the outer circle bolts of the product.

[0017] A use method of the back pressure type ultra-high pressure sealing structure, comprising:

[0018] S1, a radial sealing structure is arranged in each of the two annular grooves on the flange of the center plug;

[0019] S2, the center plug is installed into the product shell, and the center plug is fixed on the product shell by the large end bolts;

[0020] S3, the first O-ring, the first retainer, the first O-ring, and the pressure ring are sequentially sleeved on the center plug mandrel in the high-pressure shell, the pressure ring is fixed with the product shell by the bolts, and the nut is screwed on the mandrel;

[0021] S4 places the auxiliary cavity sealing structure in the groove on both sides of the upper cover step, and the upper cover is fixed on the outer circle bolt hole of the product shell through the outer circle bolt to form an auxiliary cavity between the upper end surface of the center cover and the lower end surface of the upper cover;

[0022] S5 simultaneously pressurizes the high-pressure cavity and the auxiliary cavity, and the liquid in the auxiliary cavity exerts a downward force on the center cover under the action of pressure, so as to offset the upward force on the center cover in the process of increasing the pressure of the high-pressure cavity, reduce the stress of the upper end bolt of the high-pressure cavity, and thus play a role in auxiliary support. At the same time, the force of the liquid in the auxiliary cavity on the upper cover is decomposed through the outer circle bolt on the product shell, thereby ensuring the safety of the structure of the product shell and the sealing effectiveness during the liquid pressure test of the high-pressure cavity.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] (1) The present application sets a sealing cavity between the center cover and the upper cover, which can quantitatively transfer the stress of the center cover to the upper cover, effectively reducing the stress of the center cover under the action of the pressure in the high-pressure cavity, and coordinating the stress of the large end bolt of the high-pressure cavity and the outer circle bolt. It ensures the safety of the structure and the effectiveness of the sealing during the liquid pressure test of the high-pressure cavity.

[0025] (2) The contact between the upper cover and the center cover of the present application is non-rigid contact, which can avoid the uncoordinated stress of the large end bolt and the outer circle bolt due to the structural difference between the two, the difference in bolt pre-tightening force, etc. That is, the large end bolt bears a huge force while the outer circle bolt is not stressed, and the large end bolt is not stressed. The structure is damaged due to excessive stress.

[0026] (3) The limiting action of the upper cover on the center cover in the present application increases the stiffness of the center cover and improves the safety of the center cover. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the assembly sectional view of the back pressure type ultra-high pressure sealing structure of the present application;

[0028] Figure 2 is a schematic view of the center cover structure of the present application;

[0029] Figure 3 is a schematic view of the structure of the upper cover of the present application;

[0030] Figure 4 is a partial schematic view of the auxiliary cavity of the present application;

[0031] Figure 5 is a partial schematic view of the large end sealing of the high-pressure cavity of the present application;

[0032] Figure 6 is a partial schematic view of the small end sealing of the high-pressure cavity of the present application. Detailed Implementation

[0033] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0034] This invention overcomes the problem of unreliable sealing structure performance in the prior art, and provides a back pressure type ultra-high pressure sealing structure that is reliable in sealing, easy to disassemble, and can quantitatively transmit force.

[0035] like Figures 1-6 As shown, the back pressure type ultra-high pressure sealing structure of the present invention includes a central plug 1, a nut 2, a first retaining ring 3, a first O-ring 4, a pressure ring 5, a second retaining ring 6, a second O-ring 7, an upper plug 8, an outer ring bolt 9, a large end bolt 10, an auxiliary retaining ring 11, and an auxiliary O-ring 12.

[0036] like Figure 2 As shown, the center plug 1 is welded from the flange 101 and the mandrel 102. The center plug 1 is inserted into the product housing. The flange 101 is fixed to the product housing by the large end bolt 10. The upper plug 8 is located at the top of the flange 101. The upper plug 8 is fixed to the outer ring bolt hole of the product housing by the outer ring bolt 9.

[0037] A high-pressure chamber is formed between the central plug 1 and the product housing; two annular grooves are provided on the flange, and a radial sealing structure is placed in each annular groove. Each radial seal consists of a second O-ring 7 and a second retaining ring 6, thereby achieving a seal on the large end of the high-pressure chamber. Figure 5 As shown.

[0038] A mandrel sealing structure is provided between the lower end of the mandrel 102 and the product housing. A pressure ring 5 is fitted onto the mandrel 102. Under the pressure of the nut 2, the pressure ring 5 presses against the mandrel sealing structure, achieving a seal on the small end of the high-pressure chamber. The mandrel sealing structure includes a first retaining ring 3 and two first O-rings 4. The first retaining ring 3 is located between the two first O-rings 4. The mandrel 102 cooperates with the pressure ring 5. By tightening the nut 2, the mandrel 102 presses against the first O-rings 4 and the first retaining ring 3, thus establishing an initial seal. As the pressure gradually increases, the sealing pressure of the upper first O-ring 4 on the mandrel 102 increases accordingly. The first O-ring 4 moves downwards, pressing against the first retaining ring 3 while further pressing against the lower first O-ring 4, thereby achieving a seal on the small end of the high-pressure chamber. Figure 6 As shown.

[0039] The lower end face of the upper plug 8 is provided with a step, the depth of which is 1-3mm. After installation, an auxiliary cavity 14 is formed between the upper plug 8 and the central plug 1; grooves are machined on both sides of the step of the upper plug, and an auxiliary cavity sealing structure is provided in the grooves. The auxiliary cavity sealing structure is achieved by an auxiliary retaining ring 11 and an auxiliary O-ring 12, such as... Figure 4The body 801 of the upper plug 8 is provided with two through holes which communicate with the auxiliary cavity and are connected with external pipelines through the pipe mouths 802. Figure 3

[0040] The width of the auxiliary retaining ring is equal to the depth of the groove. After the upper plug is fixed to the product shell, the auxiliary O-ring is pressed against the upper end surface of the center plug to seal the auxiliary cavity. When pressurized, the liquid first passes through the auxiliary O-ring, and after the auxiliary O-ring is extruded, the pressure is transmitted to the auxiliary retaining ring, which is elastically deformed under the action of the pressure, filling the gap between the upper plug and the center plug, effectively preventing the auxiliary O-ring from being extruded into the assembly gap and causing the seal to fail.

[0041] One of the pipe mouths of the upper plug is used to fill the auxiliary cavity with liquid under a certain pressure, and the other pipe mouth is used to exhaust the air in the auxiliary cavity to make it easier to fill the liquid.

[0042] In use, first, the two sets of second O-rings and second retaining rings are respectively sleeved in the two annular grooves on the flange of the center plug; the center plug is installed into the high-pressure shell, and the center plug is fixed to the product by the large-end bolt; then the first O-ring, the first retaining ring, the first O-ring, and the pressure ring are sequentially installed into the high-pressure cavity shell, the pressure ring is fixed to the product by the bolt, and the nut is screwed onto the mandrel to form a pre-compression; the auxiliary O-ring, the auxiliary retaining ring, and the upper plug are fixed to the product by the outer circle bolt, and the auxiliary cavity is formed between the upper end surface of the center plug and the lower end surface of the upper plug; finally, the high-pressure cavity and the auxiliary cavity are pressurized at the same time, and the stress of the center plug can be quantitatively transmitted to the upper plug according to the pressure difference between the high-pressure cavity and the auxiliary cavity.

[0043] Specifically, the use method of the back pressure type ultra-high pressure sealing structure comprises the following steps:

[0044] S1, a radial sealing structure is placed in each of the two annular grooves on the flange of the center plug;

[0045] S2, the center plug is installed into the product shell, and the center plug is fixed to the product shell by the large-end bolt;

[0046] S3, the first O-ring, the first retaining ring, the first O-ring, and the pressure ring are sequentially sleeved on the center plug mandrel in the high-pressure shell, the pressure ring is fixed to the product shell by the bolt, and the nut is screwed onto the mandrel;

[0047] S4, the auxiliary cavity sealing structure is placed in the grooves on both sides of the upper plug step, the upper plug is fixed to the outer circle bolt hole of the product shell by the outer circle bolt, and the auxiliary cavity is formed between the upper end surface of the center plug and the lower end surface of the upper plug;

[0048] ​S5 pressurizes the high-pressure cavity 13 and the auxiliary cavity 14 simultaneously, and the liquid in the auxiliary cavity 14 exerts a downward force on the center plug 1 under the action of pressure, so as to offset the upward force on the center plug 1 in the process of pressure rising of the high-pressure cavity 13, reduce the stress on the large-end bolt 10 of the high-pressure cavity 13, and thus play a role of auxiliary support. Meanwhile, the force of the liquid in the auxiliary cavity 14 on the upper plug 8 is decomposed through the outer circle bolt 9 on the product shell, so as to ensure the safety of the product shell structure and the sealing effectiveness in the process of liquid pressure test of the high-pressure cavity.

[0049] The pressure borne by the center plug is transmitted to the outer circle bolt through the upper plug, so the stress on the large-end bolt of the high-pressure cavity is greatly reduced, and the limiting effect of the upper plug on the center plug increases the rigidity of the center plug, and improves the safety of the center plug.

[0050] The present application can quantitatively transmit the force of the large-end threaded hole of the high-pressure shell to the outer circle threaded hole, which is illustrated as follows.

[0051] The large-end port diameter of the high-pressure cavity is 260 mm, and the small-end port diameter is 42 mm. The outer circle of the shell is uniformly distributed with 30 threaded holes with a specification of M18, and the large-end circle of the high-pressure cavity is uniformly distributed with 20 threaded holes with a specification of M18. The pressure of the high-pressure cavity is 92 MPa, and the average stress on the large-end bolt of the high-pressure cavity is 1.2 MN without the upper plug.

[0052]

[0053] Wherein: S is the pressure acting area in the high-pressure cavity, mm 2 ; P is the test pressure of the high-pressure cavity, MPa; and n is the number of the large-end bolt of the high-pressure cavity.

[0054] After the upper plug is adopted, the liquid with a certain pressure is introduced into the auxiliary cavity, so as to make the force borne by the large-end bolt of the high-pressure cavity and the outer circle bolt of the shell reach the minimum, and at this time, the force borne by the auxiliary cavity is

[0055]

[0056] F 总 The force borne by the center plug without the upper plug, N;

[0057]

[0058] The sealing diameter of the auxiliary cavity is 237 mm, and at this time, the force of the liquid pressure in the auxiliary cavity on the upper plug is

[0059] F2=S2·P2

[0060] That is:

[0061]

[0062] S2 = the area of the auxiliary cavity under pressure, mm 2 P2 = the pressure in the auxiliary cavity, MPa; D2 = the sealing diameter of the auxiliary cavity, mm.

[0063] Therefore, when the pressure in the high-pressure cavity reaches 92 MPa, the pressure in the auxiliary cavity is increased to 64.7 MPa, at which time the stress of the high-pressure cavity large-end bolt and the shell outer circle bolt is equal, and the average stress of 50 bolts is calculated to be 1.2 MPa.

[0064]

[0065] It can be seen that after using the upper cover, the stress of a single bolt is reduced by 59.9%.

[0066] Similarly, by adjusting the pressure of the auxiliary cavity, the stress of the high-pressure shell large-end threaded hole and the outer circle threaded hole can be quantitatively controlled, and it is a kind of sealing structure for quantitatively transmitting force.

[0067] The present application can quantitatively transmit the stress of the center cover to the upper cover by adjusting the pressure of the auxiliary cavity, effectively reducing the stress of the center cover under the action of the pressure in the high-pressure cavity, and it is a kind of ultra-high pressure sealing structure with reliable sealing, simple disassembly and quantitative force transmission.

[0068] The present application proposes a back pressure type ultra-high pressure sealing structure, which can avoid damaging the threaded hole of the metal part, and can also realize reliable sealing without changing the material of the metal part.

[0069] The present application has been described in detail in combination with specific embodiments and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that the technical solutions and embodiments of the present application can be variously replaced, modified or improved without deviating from the spirit and scope of the present application, and these all fall within the scope of the present application. The protection scope of the present application is subject to the appended claims.

[0070] The contents not described in detail in the specification of the present application are the known technology of those skilled in the art.

Claims

1. A back pressure type ultra-high pressure seal structure, characterized by, The center plug (1), nut (2), compression ring (5), upper plug (8), outer circle bolt (9), large end bolt (10); The center plug (1) is inserted into the product shell, the flange (101) is fixed with the product shell through the large end bolt (10), and the upper plug (8) is located at the top end of the flange (101). The upper plug (8) is fixed on the outer circle bolt hole of the product shell through the outer circle bolt (9); The center plug (1) and the product shell form a high pressure cavity (13); The flange (101) and the product shell are provided with two radial sealing structures to realize the sealing of the large end of the high pressure cavity; The lower end of the mandrel (102) and the product shell are provided with a mandrel sealing structure, the compression ring (5) is sleeved on the mandrel (102), the compression ring (5) is pressed under the extrusion of the nut (2) to press the mandrel sealing structure, and the sealing of the small end of the high pressure cavity is realized; The compression ring (5) is fixed with the product shell through a plurality of bolts; The lower end surface of the upper plug (8) is provided with a step, and the auxiliary cavity (14) is formed between the upper plug (8) and the center plug (1) after installation; The upper plug step outer circle and the center plug (1) are provided with an auxiliary cavity sealing structure; Two through holes are formed in the upper plug (8), which are communicated with the auxiliary cavity, and the through holes are connected with the external pipeline through the pipe mouth (802).

2. A back-pressure type ultra-high pressure seal structure according to claim 1, wherein The flange is provided with two ring grooves, and a radial sealing structure is placed in each ring groove. Each radial sealing structure is composed of a second O-shaped ring (7) and a second retainer ring (6).

3. The back-pressure type ultra-high pressure seal structure according to claim 1, wherein The mandrel sealing structure includes a first retainer ring (3) and two first O-shaped rings (4), and the first retainer ring (3) is located between the two first O-shaped rings (4); The mandrel (102) cooperates with the compression ring (5), the first O-shaped ring (4) and the first retainer ring (3) are pressed by the mandrel (102) by tightening the nut (2), so as to establish the initial sealing. With the gradual increase of pressure, the sealing specific pressure of the upper first O-shaped ring (4) of the mandrel (102) increases, and the first O-shaped ring (4) moves downward to extrude the first retainer ring (3) while further pressing the lower first O-shaped ring (4), so as to realize the sealing of the small end of the high pressure cavity.

4. The back-pressure type ultra-high pressure seal structure according to claim 1, wherein The auxiliary cavity sealing structure is realized by an auxiliary retainer ring (11) and an auxiliary O-shaped ring (12).

5. The back-pressure type ultra-high pressure seal structure according to claim 1, wherein The depth of the step on the lower end surface of the upper plug (8) is 1-3 mm.

6. The back-pressure type ultra-high pressure seal structure according to claim 1, wherein One pipe mouth on the upper plug (8) is used to fill a certain pressure liquid into the auxiliary cavity, and the other pipe mouth is used to exhaust the air in the auxiliary cavity, so that the liquid can be filled more easily.

7. The back-pressure type ultra-high pressure seal structure according to claim 1, wherein The upper plug (8) and the center plug (1) belong to non-rigid contact, and by reasonably adjusting the pressure between the high pressure cavity (13) and the auxiliary cavity (14), the force on the large end thread hole of the high pressure cavity can be quantitatively transmitted to the product outer circle bolt (9).

8. A method of using a back pressure ultra-high pressure seal structure, characterized by, The center plug (1), nut (2), compression ring (5), upper plug (8), outer circle bolt (9), large end bolt (10); The center plug (1) is welded by a flange (101) and a mandrel (102), the center plug (1) is inserted into a product shell, the flange (101) is fixed to the product shell by a large end bolt (10), and an upper plug (8) is located at the top end of the flange (101), and the upper plug (8) is fixed to the outer circle bolt hole of the product shell by an outer circle bolt (9); A high-pressure cavity (13) is formed between the center plug (1) and the product shell, and two radial sealing structures are arranged between the flange (101) and the product shell to seal the large end of the high-pressure cavity; A mandrel sealing structure is arranged between the lower end of the mandrel (102) and the product shell, a compression ring (5) is sleeved on the mandrel (102), the compression ring (5) is pressed against the mandrel sealing structure under the extrusion of a nut (2), and the small end of the high-pressure cavity is sealed; the compression ring (5) is fixed to the product shell by a plurality of bolts; A step is arranged on the lower end surface of the upper plug (8), an auxiliary cavity (14) is formed between the upper plug (8) and the center plug (1) after installation, an auxiliary cavity sealing structure is arranged between the outer circle of the upper plug step and the center plug (1), and two through holes are formed in the upper plug (8) and communicate with the auxiliary cavity, and the through holes are connected with external pipelines through pipe mouths (802); Two ring grooves are arranged on the flange, and a radial sealing structure is arranged in each ring groove, and each radial sealing structure is composed of a second O-shaped ring (7) and a second retainer ring (6); The mandrel sealing structure comprises a first retainer ring (3) and two first O-shaped rings (4), and the first retainer ring (3) is located between the two first O-shaped rings (4); The use method comprises the following steps: S1, a radial sealing structure is arranged in each of the two ring grooves on the flange of the center plug; S2, the center plug is installed in the product shell, and the center plug is fixed to the product shell by the large end bolt; S3, the first O-shaped ring, the first retainer ring, the first O-shaped ring and the compression ring are sequentially sleeved on the mandrel of the center plug in the product shell, the compression ring is fixed to the product shell by the bolt, and the nut is screwed on the mandrel; S4, the auxiliary cavity sealing structure is arranged in the recesses on both sides of the upper plug step, the upper plug is fixed to the outer circle bolt hole of the product shell by the outer circle bolt, and the auxiliary cavity is formed between the upper end surface of the center plug and the lower end surface of the upper plug; S5, the high-pressure cavity (13) and the auxiliary cavity (14) are simultaneously pressurized, the liquid in the auxiliary cavity (14) exerts a downward force on the center plug (1) under the action of pressure, so as to offset the upward force on the center plug (1) in the pressure increasing process of the high-pressure cavity (13), reduce the stress on the large end bolt (10) of the high-pressure cavity (13), and play a supporting role, and the force of the liquid in the auxiliary cavity (14) on the upper plug (8) is decomposed by the outer circle bolt (9) on the product shell, so as to ensure the safety and sealing effectiveness of the product shell structure in the liquid pressure test process of the high-pressure cavity.

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