Unloading type low-temperature throttling stop valve and machining method of valve body assembly

Abstract

The invention discloses an unloading type low-temperature throttling stop valve and a machining method of a valve body assembly, and the unloading type low-temperature throttling stop valve comprises the valve body assembly, a valve rod assembly and an auxiliary valve element assembly; a flowing cavity is formed in the valve body assembly, the valve rod assembly can be arranged in the valve body assembly in a piston motion mode in the vertical direction, the valve body assembly is further provided with an inlet channel and an outlet channel which are communicated with the flowing cavity, and a sealing gasket is arranged at the bottom end of the valve rod assembly. The sealing gasket can abut against a sealing cutting edge at the communicating position of the inlet channel and the flowing cavity along with descending of the valve rod assembly so that face sealing can be formed. When the stop valve is used, the problems that a sealing structure of a stop valve in the prior art fails and the like are solved, and when the stop valve is closed, fluid in a cavity of the stop valve can cause the large pressure difference of an inlet and an outlet in the closing process, the closing torque of the valve in the closing process is influenced, and the rapid response of a system is greatly influenced are solved.

Description

Technical Field

[0001] The invention relates to the technical field of manual stop valves, and in particular to a method for processing a load-relief type low-temperature throttling stop valve and a valve body assembly. Background Art

[0002] As a forced-sealed valve, the stop valve mainly plays a cutting role in the pipeline system and is widely used in industry and production life. It has a large opening and closing torque, a long structural dimension, a small opening height during the switching process, and can easily adjust the flow rate. It can realize functions such as medium transportation, cutoff, and regulation. It plays an important role in the high-pressure system in the aerospace field.

[0003] When the stop valve is in the closed state, the valve seat edge and the valve core sealing surface are forced to contact to achieve a sealing effect. Due to the gradual popularization of high-pressure use in rocket propulsion systems at this stage, traditional stop valves often have sealing structure failures and other phenomena. In addition, the manual stop valve is in an open state most of the time in the system. When the valve after the system does not require flow, the closing speed of the stop valve is very important. When the stop valve is closed, the fluid in the stop valve cavity will cause the inlet and outlet pressure difference to increase during the closing process, affecting the closing torque of the valve during the closing process, and having a greater impact on the rapid response of the system. Therefore, a processing method for a unloading low-temperature throttling stop valve and a valve body assembly is proposed to solve the above-mentioned problems. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems that the sealing structure of the stop valve in the prior art may fail, and when the stop valve is closed, the fluid in the stop valve cavity will cause the inlet and outlet pressure difference to increase during the closing process, affecting the closing torque of the valve during the closing process, and causing a significant impact on the rapid response of the system, thereby providing a unloading low-temperature throttling stop valve and a processing method for a valve body assembly that can solve the above technical problems.

[0005] In order to achieve the above-mentioned object, the present invention provides a unloading type low temperature throttling stop valve, which comprises: a valve body assembly, a valve stem assembly and a secondary valve core assembly; wherein,

[0006] A flow cavity is formed inside the valve body assembly, the valve stem assembly can be arranged inside the valve body assembly in a piston-like manner along a vertical direction, the valve body assembly is also provided with an inlet channel and an outlet channel respectively connected to the flow cavity, and a sealing gasket is provided at the bottom end of the valve stem assembly, and the sealing gasket can follow the descent of the valve stem assembly to abut against the sealing edge at the connection between the inlet channel and the flow cavity to form a surface seal, and the auxiliary valve core assembly is arranged in the inlet channel; wherein,

[0007] The auxiliary valve core assembly includes: a valve seat, an auxiliary valve core and an elastic assembly; the inner side of the auxiliary valve core can be slidably assembled in the inlet channel along the central axis direction of the inlet channel through the elastic assembly, the valve seat is fixedly assembled at the entrance of the inlet channel, and the outer side of the auxiliary valve core can abut against the valve seat to form a surface seal.

[0008] Preferably, a plurality of groups of inclined hole flow channels are arranged on the side of the auxiliary valve core, and one side of the sealing surface is squeezed and sealed by the cutting edge of the valve seat, and the other side opposite thereto is fixed and limited by the elastic component.

[0009] Preferably, the elastic component is a bellows.

[0010] Preferably, the valve body assembly includes: a shell, a cylinder and a locking nut; the shell and the cylinder are connected together by bolts, and the valve stem assembly is respectively assembled with the locking nut and the cylinder through a threaded structure; the auxiliary valve core assembly is installed in the shell, and the interior of the cylinder is also threadedly equipped with an anti-twist plate.

[0011] Preferably, the valve stem assembly comprises: a valve stem body, a screw rod and a hand wheel;

[0012] The valve stem body and the screw are slidably connected through the step through hole at the bottom of the screw, and the screw is respectively assembled with the locking nut and the cylinder through a threaded structure. The top end of the screw extends out of the locking nut, and the middle part of the hand wheel is sleeved on the top end of the screw and locked by a cap;

[0013] The anti-twist plate is slidably assembled with the valve stem body, the anti-twist plate is processed into a boss, the valve stem body is processed with a flat position at the step to form a limit with the anti-twist plate, thereby ensuring that the valve stem body can only move up and down, and an interval stroke is set between the anti-twist plate and the screw, so that the sealing surface of the valve stem body and the sealing edge of the flow cavity can be squeezed, thereby ensuring the sealing performance of the stop valve in a high-pressure environment.

[0014] Preferably, the inner wall portion of the cylinder is recessed inward to form at least two groups of annular grooves, each group of the annular grooves is provided with an O-ring and a retaining ring, and the retaining ring is installed above the O-ring to limit the O-ring to ensure the sealing between the inner wall of the cylinder and the valve stem body.

[0015] Preferably, the sealing gasket is made of fluoroethylene propylene material.

[0016] Preferably, after the elastic component, auxiliary valve core and valve seat are installed in the outlet channel of the shell in sequence, the shell and the valve seat are welded by argon arc welding, and then the shell is cryogenically treated to ensure the sealing of the shell welding parts in a low temperature environment.

[0017] Preferably, the valve stem assembly and the auxiliary valve core assembly need to undergo at least two cryogenic treatments before and after processing.

[0018] The present invention also provides a method for processing a valve body assembly, the method comprising:

[0019] Step S1, subjecting the raw sealing gasket to cryogenic treatment before processing, soaking it in liquid nitrogen for 3-5 hours and then placing it at room temperature for another 3-5 hours;

[0020] Step S2, first drying the hot pressing tooling, fixing the cryogenically treated sealing gasket blank and the annular dovetail groove at the bottom of the valve stem body through the hot pressing tooling, placing the hot pressed part in a hot press, and using high temperature to melt the sealing gasket blank and the annular dovetail groove at the bottom of the valve stem body into a whole, when the temperature in the hot press rises to the first preset temperature, it is necessary to keep it warm for 20-30 minutes to prevent bubbles from appearing in the sealing gasket; after lowering the temperature in the hot press to the second preset temperature, applying a preset pressure to the hot pressing mold until the preset demolding temperature is reached for demolding;

[0021] Step S3, subjecting the hot-pressed valve stem body blank to a second deep-cold treatment, soaking it in liquid nitrogen for 3-5 hours and then placing it at room temperature for another 3-5 hours;

[0022] Step S4, machining the valve stem body after the secondary cryogenic treatment to obtain a final valve stem assembly.

[0023] According to the above technical scheme, the beneficial effect of the unloading type low-temperature throttling stop valve provided by the present invention when in use is: the pressure difference before and after the main valve core of the stop valve is controlled by the unloading structure, thereby reducing the torque during the closing process of the stop valve, which can effectively improve the rapid response efficiency of the system, and through the structural improvement of the auxiliary valve core component, the change of the front and rear flow channels can be controlled by the stable elasticity of the elastic component to achieve the effect of pressure reduction and throttling of the stop valve.

[0024] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation mode; and the parts not involved in the present invention are the same as the prior art or can be implemented by using the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 It is a schematic diagram of the cross-sectional structure in the vertical direction of a unloading type low-temperature throttling stop valve provided in a preferred embodiment of the present invention;

[0027] Figure 2It is a schematic diagram of the communication structure of the flow cavity, the inlet channel and the outlet channel of the unloading type low temperature throttling stop valve provided in a preferred embodiment of the present invention;

[0028] Figure 3 The structure of the valve stem body of the unloading type low temperature throttling stop valve provided in a preferred embodiment of the present invention is schematically shown. Figure 1 ;

[0029] Figure 4 The structure diagram of the valve stem body of a unloading type low temperature throttling stop valve provided in a preferred embodiment of the present invention is Figure 2 ;

[0030] Figure 5 yes Figure 1 The enlarged view of point A in the middle;

[0031] Figure 6 yes Figure 1 The enlarged view of point B in the middle;

[0032] Figure 7 It is a flow chart of a method for processing a valve body assembly provided in a preferred embodiment of the present invention.

[0033] Description of Reference Numerals

[0034] 1 stem body 2 housing

[0035] 3 valve core components 4 cylinders

[0036] 5 locking nut 6 screw

[0037] 7 Anti-twist plate 8 Handwheel

[0038] 9 cap 10 O-ring

[0039] 11 retaining ring 102 sealing gasket

[0040] 103 annular dovetail groove 201 sealing edge

[0041] 202 inlet channel 203 flow chamber

[0042] 204 outlet channel 301 valve seat

[0043] 302 auxiliary valve core 303 elastic component DETAILED DESCRIPTION

[0044] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0045] In the present invention, unless otherwise stated, directional words such as "upper, lower, inside, outside" contained in a term merely represent the orientation of the term in normal usage, or are common names understood by those skilled in the art, and should not be regarded as limitations on the term.

[0046] like Figure 1-6 As shown, the present invention provides a unloading type low temperature throttling stop valve, characterized in that the unloading type low temperature throttling stop valve comprises: a valve body assembly, a valve stem assembly and a secondary valve core assembly 3; wherein,

[0047] A flow cavity 203 is formed inside the valve body assembly, and the valve stem assembly can be arranged inside the valve body assembly in a piston-like manner along the vertical direction. The valve body assembly is also provided with an inlet channel 202 and an outlet channel 204 respectively connected to the flow cavity 203, and a sealing gasket 102 is provided at the bottom end of the valve stem assembly, and the sealing gasket 102 can follow the descent of the valve stem assembly to abut against the sealing edge 201 at the connection between the inlet channel 202 and the flow cavity 203 to form a surface seal, and the auxiliary valve core assembly 3 is arranged in the inlet channel 202; wherein,

[0048] The auxiliary valve core assembly 3 includes: a valve seat 301, an auxiliary valve core 302 and an elastic assembly 303; the inner side of the auxiliary valve core 302 can be slidably assembled in the inlet channel 202 along the central axis direction of the inlet channel 202 through the elastic assembly 303, the valve seat 301 is fixedly assembled at the entrance of the inlet channel 202, and the outer side of the auxiliary valve core 302 can abut against the valve seat 301 to form a surface seal.

[0049] In the above scheme, before the stop valve is opened, the fluid flows in through the valve seat 301 channel. At this time, the pressure in the flow channel between the auxiliary valve core 302 and the valve stem assembly is zero. Since the inlet pressure is greater than the elastic force of the elastic component, the fluid can flow in. After the fluid flows in for a period of time, the front and rear pressure difference gradually decreases. At this time, the elastic force of the elastic component is greater than the inlet pressure. Under the squeezing effect of the bellows elastic component, the auxiliary valve core 302 gradually forms a seal with the valve seat 301. When the stop valve is opened, the valve stem assembly is rotated to open. At this time, due to the increase in the flow channel, the inlet pressure is greater than the elastic force of the elastic component, allowing the fluid to continue to flow in. After the fluid enters from the inlet channel 202, it is subjected to the front and rear pressures of the inlet channel 202 and the outlet channel 204. Due to the difference, the fluid flows through the inner cavity 203 of the shell and flows out from the outlet channel 204. After the fluid flows in for a period of time, the inlet pressure and the outlet pressure are gradually balanced; when the stop valve is closed, the valve stem assembly is operated to close the stop valve. At this time, the inlet pressure is greater than the outlet pressure again, but due to the action of the auxiliary valve core 302 and the elastic component 303, the fluid is subject to a certain throttling effect at the auxiliary valve core 302. This process also reduces the thread torque of the stop valve during the closing process. Finally, the sealing surface of the valve stem assembly is squeezed and sealed with the step edge 201, so that the fluid medium is quickly throttled at the step edge 201 to close the stop valve. In this process, the closing problem of the stop valve is effectively improved through the main and auxiliary sealing structures.

[0050] In the above scheme, when the unloading type low-temperature throttling stop valve provided by the present invention is in use, the pressure difference before and after the main valve core of the stop valve is controlled by the unloading structure, thereby reducing the torque during the closing process of the stop valve, which can effectively improve the rapid response efficiency of the system. Moreover, through the structural improvement of the auxiliary valve core component, the change of the front and rear flow channels can be controlled by the stable elasticity of the elastic component to achieve the effect of pressure reduction and throttling of the stop valve.

[0051] In a preferred embodiment of the present invention, a plurality of groups of inclined hole flow channels are arranged on the side of the auxiliary valve core 302 , and one side of its sealing surface is squeezed and sealed by the cutting edge of the valve seat 301 , and the other side thereof is fixed and limited by the elastic component 303 .

[0052] Preferably, the elastic component 303 is a bellows.

[0053] In the above scheme, since the maximum and minimum deformation of the bellows is relatively fixed, the pressure change range is reduced compared with other elastic elements such as springs when the pressure increases or decreases, which can ensure and improve the safety and stability of the valve during use.

[0054] In a preferred embodiment of the present invention, the valve body assembly comprises: a housing 2, a cylinder 4 and a locking nut 5; the housing 2 and the cylinder 4 are connected together by bolts, and the valve stem assembly 1 is respectively assembled with the locking nut 5 and the cylinder 4 by a threaded structure; the auxiliary valve core assembly 3 is installed in the housing 2, and the interior of the cylinder 4 is also threadedly assembled with an anti-twist plate 7;

[0055] The valve stem assembly includes: a valve stem body 1, a screw rod 6 and a hand wheel 8; the valve stem body 1 and the screw rod 6 are slidably connected through the step through hole at the bottom of the screw rod 6, and the screw rod 6 is respectively assembled with the locking top nut 5 and the cylinder 4 through a threaded structure, the top end of the screw rod 6 extends out from the locking top nut 5, and the middle part of the hand wheel 8 is sleeved on the top end of the screw rod 6 and locked by a cap 9;

[0056] The anti-twist plate 7 is slidably assembled with the valve stem body 1, and the anti-twist plate 7 is processed into a boss. The valve stem body 1 is processed with a flat position at the step to form a limit with the anti-twist plate 7, thereby ensuring that the valve stem body 1 can only move up and down, and an interval stroke is set between the anti-twist plate 7 and the screw 6, so that the sealing surface of the valve stem body 1 and the sealing edge of the flow cavity 203 can be squeezed, thereby ensuring the sealing performance of the stop valve in a high-pressure environment.

[0057] In the above scheme, when the stop valve is opened, the screw 6 is driven by rotating the hand wheel 8, and the trapezoidal thread of the inner cavity of the locking top nut 5 is used to drive the valve stem assembly 1 to rise, thereby opening the main valve core. At this time, due to the increase in the flow channel, when the fluid flows in for a period of time, the inlet pressure and the outlet pressure gradually balance; when the stop valve is closed, the trapezoidal thread of the locking top nut 5 drives the valve stem assembly 1 to descend, thereby closing the stop valve; the torque MFL when the valve is closed is mainly affected by the friction torque of the valve stem nut, that is, MFL=F×RFM, where the total axial force F of the valve stem is composed of the medium force on the sealing surface, the sealing force on the sealing surface, the friction between the valve stem and the packing, and the friction of the anti-twist plate. The medium force is the reaction force generated by the contact between the fluid medium in the valve body and the valve disc during the closing process of the valve stem. This force acts directly on the sealing surface, and its magnitude depends on the pressure of the fluid and the area under force. The formula for the medium force is F MJ =0.785×D MN +b M 2 ×P. Among them, F MJ is the medium force; D MN b is the inner diameter of the sealing surface; M is the calculated width of the sealing surface; P is the nominal pressure of the valve. Therefore, controlling the inlet pressure can reduce the medium force F, reduce the torque when the valve is closed, and improve the response of the valve when it is closed.

[0058] The anti-twist plate 7 is fixed to the inner plane of the cylinder by threads, and the valve stem body 1 is processed into a flat step at the upper step. The anti-twist plate 7 is in surface contact with the valve stem body 1 to ensure that the valve stem body 1 can only move up and down. At the same time, the stroke between the anti-twist plate 7 and the screw 5 is 0.1mm, so that the sealing surface of the valve stem assembly 1 and the step edge 201 are squeezed to a certain extent, thereby ensuring the sealing performance of the stop valve in a high-pressure environment.

[0059] In a preferred embodiment of the present invention, the inner wall portion of the cylinder 4 is recessed inward to form at least two groups of annular grooves, each group of the annular grooves is provided with an O-ring 10 and a retaining ring 11, and the retaining ring 11 is installed above the O-ring 10 to limit the O-ring 10 to ensure the sealing between the inner wall of the cylinder 4 and the valve stem body 1;

[0060] In a preferred embodiment of the present invention, the sealing gasket 102 is made of fluoroethylene propylene material.

[0061] In a preferred embodiment of the present invention, after the elastic component 303, the auxiliary valve core 302 and the valve seat 301 are sequentially installed in the outlet channel 204 of the shell 2, the shell 2 and the valve seat 301 are welded by argon arc welding, and then the shell 2 is cryogenically treated to ensure the sealing of the shell welding parts under low temperature environment.

[0062] In a preferred embodiment of the present invention, the valve stem assembly and the auxiliary valve core assembly 3 need to undergo at least two cryogenic treatments before and after processing.

[0063] In the above scheme, the sealing gasket 102 uses polytetrafluoroethylene propylene F462 as the sealing surface material, the sealing gasket 102 and the sealing groove are installed by hot pressing, the sealing gasket 102 is fixed in the dovetail groove by hot pressing tooling, and the sealing surface of the blank is processed by two deep cold treatments to ensure that its surface finish is 0.2, and the step edge structure can effectively improve the sealing failure problem of the stop valve. Figure 3 and Figure 4 As shown, the assembly structure of the sealing gasket 102 and the end of the valve stem body 1 can have two structures, one is that the sealing gasket is only arranged in the dovetail groove, and the other is that the sealing gasket is not only arranged in the dovetail groove but also covers the bottom end surface of the valve stem body 1. Both structures can ensure the sealing effect between the end of the valve stem body 1 and the sealing edge 201.

[0064] In the present application, polyperfluoroethylene propylene material is used for sealing, and the sealing surface processed by cryogenic treatment and hot pressing process can effectively seal in a low temperature environment. At the same time, the working condition is made to flow in a bottom-in and top-out manner, which can effectively ensure the sealing of the stop valve in a high-pressure environment.

[0065] In summary, the working principle of the stop valve provided by the present invention is as follows: before the stop valve is opened, the fluid flows in through the valve seat 301 channel. At this time, the pressure in the flow channel between the auxiliary valve core 302 and the valve stem body 1 is zero. Since the inlet pressure is greater than the bellows force, the fluid can flow in. After the fluid flows in for a period of time, the front and rear pressure difference gradually decreases. At this time, the bellows force is greater than the inlet pressure. Under the squeezing effect of the bellows assembly 303, the auxiliary valve core 302 gradually forms and finally forms a seal with the valve seat 301; when the stop valve is opened, the hand wheel 8 is rotated to drive the screw 6, and the trapezoidal thread of the inner cavity of the locking top nut 5 is used to drive the valve stem body 1 to rise, thereby opening the main valve core. At this time, due to the increase in the flow channel, the inlet pressure is greater than the bellows force, so that the fluid continues to flow in. After the fluid enters from the inlet channel 202, it is affected by the front and rear pressure difference between the inlet channel 202 and the outlet channel 204, and flows through the inner cavity 203 of the shell and out of the outlet channel 20 4 flows out, and the fluid in the housing cavity 203 is sealed by the O-ring 10 and the retaining ring 11 and circulates only in the inlet channel 202, the housing cavity 203 and the outlet channel 204. After the fluid flows in for a period of time, the inlet pressure and the outlet pressure are gradually balanced; when the stop valve is closed, the trapezoidal thread of the locking top nut 5 drives the valve stem body 1 to descend, thereby closing the stop valve. At this time, the inlet pressure is greater than the outlet pressure again, but due to the action of the auxiliary valve core 302 and the bellows assembly 303, the fluid is subject to a certain throttling effect at the auxiliary valve core 302. This process also reduces the thread torque of the stop valve during the closing process. Finally, the sealing surface of the valve stem body 1 and the step edge 201 are squeezed and sealed by the torque of the screw 6, so that the fluid medium is quickly throttled at the step edge 201 to close the stop valve. In this process, the closing problem of the stop valve is effectively improved through the main and auxiliary sealing structures.

[0066] like Figure 7 As shown, the present invention also provides a method for processing a valve body assembly, characterized in that the processing method comprises:

[0067] Step S1, subjecting the raw seal gasket 102 before processing to cryogenic treatment, soaking it in liquid nitrogen for 3-5 hours and then placing it at room temperature for another 3-5 hours;

[0068] Step S2, drying the hot pressing tooling, fixing the blank of the sealing gasket 102 after deep freezing treatment with the annular dovetail groove 103 at the bottom of the valve stem body 1 through the hot pressing tooling, placing the hot pressed part in a hot press, and using high temperature to melt the blank of the sealing gasket 102 and the annular dovetail groove 103 at the bottom of the valve stem body 1 into a whole, when the temperature in the hot press rises to the first preset temperature, it is necessary to keep it warm for 20-30 minutes to prevent bubbles from appearing in the sealing gasket; after lowering the temperature in the hot press to the second preset temperature, applying a preset pressure to the hot pressing mold until the preset demolding temperature is reached for demolding;

[0069] Step S3, subjecting the hot-pressed valve stem body 1 blank to a second deep-cold treatment, soaking it in liquid nitrogen for 3-5 hours and then placing it at room temperature for another 3-5 hours;

[0070] Step S4, machining the valve stem body 1 after the secondary cryogenic treatment to obtain a final valve stem assembly.

[0071] In the above scheme, the valve body assembly is formed by secondary cryogenic treatment. The sealing surface processed by cryogenic treatment and hot pressing process can be effectively sealed in a low temperature environment. At the same time, the working condition flows in a bottom-in and top-out manner, which can effectively ensure the sealing of the stop valve in a high-pressure environment.

[0072] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0073] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0074] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A unloading type low temperature throttling stop valve, characterized in that: The unloading type low temperature throttling stop valve comprises: a valve body assembly, a valve stem assembly and a secondary valve core assembly (3); wherein, A flow cavity (203) is formed inside the valve body assembly, the valve stem assembly can be arranged inside the valve body assembly in a piston-like manner along a vertical direction, and the valve body assembly is also provided with an inlet channel (202) and an outlet channel (204) respectively connected to the flow cavity (203), and a sealing gasket (102) is provided at the bottom end of the valve stem assembly, and the sealing gasket (102) can follow the descent of the valve stem assembly to abut against a sealing edge (201) at the connection between the inlet channel (202) and the flow cavity (203) to form a surface seal, and the auxiliary valve core assembly (3) is arranged in the inlet channel (202); wherein, The auxiliary valve core assembly (3) comprises: a valve seat (301), an auxiliary valve core (302) and an elastic assembly (303); the inner side of the auxiliary valve core (302) can be slidably assembled in the inlet channel (202) along the central axis direction of the inlet channel (202) through the elastic assembly (303), the valve seat (301) is fixedly assembled at the entrance of the inlet channel (202), and the outer side of the auxiliary valve core (302) can be abutted against the valve seat (301) to form a surface seal.

2. The unloading type low temperature throttling stop valve according to claim 1, characterized in that: A plurality of groups of inclined hole flow channels are arranged on the side of the auxiliary valve core (302), and one side of its sealing surface is squeezed and sealed by the cutting edge of the valve seat (301), while the other side opposite thereto is fixed and limited by the elastic component (303).

3. The unloading type low temperature throttling stop valve according to claim 2 is characterized in that: The elastic component (303) is a bellows.

4. The unloading type low temperature throttling stop valve according to claim 1, characterized in that: The valve body assembly comprises: a housing (2), a cylinder (4) and a locking nut (5); the housing (2) and the cylinder (4) are connected together by bolts, and the valve stem assembly (1) is respectively assembled with the locking nut (5) and the cylinder (4) by a threaded structure; the auxiliary valve core assembly (3) is installed in the housing (2), and the interior of the cylinder (4) is also threadedly assembled with an anti-twist plate (7).

5. The unloading type low temperature throttling stop valve according to claim 4, characterized in that: The valve stem assembly comprises: a valve stem body (1), a screw rod (6) and a hand wheel (8); The valve stem body (1) and the screw rod (6) are slidably connected via a stepped through hole at the bottom of the screw rod (6); the screw rod (6) is respectively assembled with the locking nut (5) and the cylinder (4) via a threaded structure; the top end of the screw rod (6) extends out from the locking nut (5); the middle part of the hand wheel (8) is sleeved on the top end of the screw rod (6) and is locked via a cap (9); The anti-twist plate (7) is slidably assembled with the valve stem body (1), the anti-twist plate (7) is processed into a boss, the valve stem body (1) is processed with a flat position at the step to form a limit with the anti-twist plate (7), thereby ensuring that the valve stem body (1) can only move up and down, and an interval stroke is set between the anti-twist plate (7) and the screw (6) so that the sealing surface of the valve stem body (1) and the sealing edge of the flow cavity (203) can be squeezed, thereby ensuring the sealing performance of the stop valve in a high-pressure environment.

6. The unloading type low temperature throttling stop valve according to claim 4, characterized in that: The inner wall of the cylinder (4) is recessed inward to form at least two groups of annular grooves, each group of the annular grooves is provided with an O-ring (10) and a retaining ring (11), and the retaining ring (11) is installed above the O-ring (10) to limit the O-ring (10) to ensure the sealing between the inner wall of the cylinder (4) and the valve stem body (1).

7. The unloading type low temperature throttling stop valve according to claim 1, characterized in that: The sealing gasket (102) is made of fluoroethylene propylene material.

8. The unloading type low temperature throttling stop valve according to claim 4, characterized in that: After the elastic component (303), the auxiliary valve core (302) and the valve seat (301) are sequentially installed in the outlet channel (204) of the shell (2), the shell (2) and the valve seat (301) are welded by argon arc welding, and then the shell (2) is cryogenically treated to ensure the sealing of the shell welding part in a low-temperature environment.

9. The unloading type low temperature throttling stop valve according to claim 1, characterized in that: The valve stem assembly and the auxiliary valve core assembly (3) need to undergo at least two cryogenic treatments before and after processing.

10. A method for processing a valve body assembly according to any one of claims 1 to 9, characterized in that: The processing method comprises: Step S1, subjecting the raw seal gasket (102) to cryogenic treatment before processing, soaking it in liquid nitrogen for 3-5 hours and then placing it at room temperature for another 3-5 hours; Step S2, first drying the hot pressing tooling, fixing the blank of the sealing gasket (102) after deep freezing treatment with the annular dovetail groove (103) at the bottom of the valve stem body (1) through the hot pressing tooling, placing the hot pressed part in a hot press, and using high temperature to melt the blank of the sealing gasket (102) and the annular dovetail groove (103) at the bottom of the valve stem body (1) into a whole, when the temperature in the hot press rises to a first preset temperature, it is necessary to keep it warm for 20-30 minutes to prevent bubbles from appearing in the sealing gasket; after lowering the temperature in the hot press to a second preset temperature, applying a preset pressure to the hot pressing mold until the preset demolding temperature is reached for demolding; Step S3, subjecting the hot-pressed valve stem body (1) blank to a second deep-cold treatment, soaking it in liquid nitrogen for 3-5 hours and then placing it at room temperature for another 3-5 hours; Step S4, machining the valve stem body (1) after the secondary cryogenic treatment to obtain a final valve stem assembly.

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