Method for machining a planetary roller screw pair for nuclear power

Abstract

The application discloses a machining method of a planetary roller screw pair for nuclear power, and the planetary roller screw pair comprises a planetary roller screw and a driving assembly. The planetary roller screw comprises a screw and a screw nut assembly, further comprises a sealing sleeve, and the outer sleeve of the screw nut assembly is coaxially installed in the sealing sleeve through a rolling bearing. The output end of the driving assembly drives the outer sleeve to rotate. The driving assembly is connected to the end of the sealing sleeve and serves as an end sealing element of the sealing sleeve. The machining method comprises an assembly method of the planetary roller screw pair: S1, preparing parts; S2, completing the installation of the screw nut assembly in the sealing sleeve; performing the assembly of the screw and the screw nut assembly; and S3, completing the connection between the driving assembly and the end of the sealing sleeve and the screw nut assembly. The structure obtained by the machining method can not only optimize the radiation material leakage problem of the valve for nuclear power, but also simplify the valve structure, which is favorable for the radiation protection treatment of the valve after the valve is retired.

Description

TECHNICAL FIELD

[0001] The application relates to a valve driving structure technical field, in particular to a machining method of a planetary roller screw pair for nuclear power. BACKGROUND

[0002] In the prior art, the planetary roller screw and the ball screw can be used as components of a transmission mechanism, and the two have the characteristics of ensuring transmission accuracy and transmission stability.

[0003] The planetary roller screw and the ball screw are similar in structure. The planetary roller screw comprises a screw nut assembly and a screw. The screw is a multi-start threaded screw. The screw nut assembly comprises a sleeve, planetary rollers and a baffle. The sleeve is provided with a planetary gear ring at both ends. The inner side of the sleeve is provided with threads. The planetary gear type at both ends of the planetary roller is in mesh with the planetary gear ring. The threads on the planetary roller are in mesh with the threads on the sleeve and the screw. The typical difference between the planetary roller screw and the ball screw lies in that the load transmission element of the planetary roller screw is a planetary roller, and the contact surface form in the load transmission process is a typical line contact. The load transmission element of the ball screw is a ball, and the contact form in the load transmission process is point contact. Therefore, in specific application, the main advantage of the planetary roller screw is that it has a larger contact area to transmit load, which makes the planetary roller screw have outstanding advantages in service life, load transmission capacity, impact resistance and reliability compared with the ball screw.

[0004] In the prior art, the use of the planetary roller screw includes the technical solutions provided in patent application files such as CN201510548911.2 and CN201810726919.7.

[0005] In the technical solution provided in the patent application file with the application number CN201810726919.7, as recorded in paragraph 0032 of the specification, a roller screw mechanism is used in a valve transmission mechanism. According to other records in the patent application file, it can be reasonably inferred that when the servo motor rotates, the planetary carrier drives the roller screw (the screw mentioned above) to rotate. The roller screw drives the roller nut (the screw nut assembly mentioned above) to move linearly along the axis of the roller screw. The push rod connected to the roller nut moves synchronously with the roller nut, thereby achieving the purpose of changing the opening and closing state of the valve connected to the push rod connector.

[0006] As described above, the roller screw mechanism in the prior art has been used in valve driving mechanisms, and these valves have the characteristics of high reliability, high flow regulation accuracy, long service life, good structural rigidity, and short valve action time, which are different from the transmission valve driving structure. Further structural optimization of the planetary roller screw pair used in the valve and the related processing method have important significance for the development of valve technology. SUMMARY

[0007] In view of the above, the further structural optimization of the planetary roller screw pair used in the valve and the related processing method have important significance for the development of valve technology, and the present application provides a nuclear power planetary roller screw pair processing method. The present application provides a planetary roller screw pair processing method, and the structure of the planetary roller screw pair obtained by using the present application can not only optimize the leakage of radioactive substances of the nuclear power valve, but also simplify the structure of the valve, which is beneficial to the radiation protection treatment of the valve after retirement.

[0008] In view of the above, the further structural optimization of the planetary roller screw pair used in the valve and the related processing method have important significance for the development of valve technology, and the present application provides a nuclear power planetary roller screw pair processing method. The present application provides a planetary roller screw pair processing method, and the structure of the planetary roller screw pair obtained by using the present application can not only optimize the leakage of radioactive substances of the nuclear power valve, but also simplify the structure of the valve, which is beneficial to the radiation protection treatment of the valve after retirement.

[0009] The driving assembly is connected to the end of the sealing sleeve, and the driving assembly serves as an end sealing member of the sealing sleeve.

[0010] The driving assembly is connected to the end of the sealing sleeve, and the driving assembly serves as an end sealing member of the sealing sleeve.

[0011] The driving assembly is connected to the end of the sealing sleeve, and the driving assembly serves as an end sealing member of the sealing sleeve.

[0012] The processing method includes the assembly method of the planetary roller screw pair, specifically:

[0013] S1, preparing each component of the planetary roller screw pair;

[0014] S2, installing the nut assembly in the sealing sleeve through the rolling bearing; and installing the screw and the nut assembly in cooperation;

[0015] S3, connecting the driving assembly to the end of the sealing sleeve, and connecting the output end of the driving assembly to the nut assembly.

[0016] In the prior art, as provided in the technical solution of application No. CN201810726919.7, the planetary roller screw has the advantages of service life, load transmission and structural stability. When used as a valve driving mechanism, it can effectively ensure the reliability of the valve and reduce the valve cutoff time required in emergency situations. As a valve that changes the opening and closing state of the valve through linear motion, it is usually necessary to convert the rotary motion of the driving mechanism into linear motion of the valve plate. As provided in the technical solution of application No. CN201810726919.7, in order to enable the valve connected to the push rod joint to perform opening and closing actions, the action process is as follows: the servo motor rotates, the planetary carrier drives the roller screw to rotate, the roller screw drives the roller nut to move linearly along the axis of the roller screw, the push rod connected to the roller nut moves synchronously with the roller nut, and the opening and closing state of the valve connected to the push rod joint changes. In addition, when the planetary roller screw is used as a component part of other linear actuators, as provided in the technical solution of application No. CN201510548911.2, in order to obtain linear motion of the object acted upon, the scheme still uses a motor to drive a screw, the screw drives a planetary nut to move linearly along a sleeve (guide sleeve), and the push rod connected to the planetary nut acts on the object to be executed. In the structure provided by the above prior art, in addition to the structure of the planetary roller screw itself, a push rod is also included. At the same time, when the planetary roller screw is used to drive the valve action, the push rod is connected to the valve plate, and the space where the valve plate is located is in communication with the fluid environment of the pipeline. In order to avoid or reduce fluid leakage, a sealing structure is necessary. The sealing structure at the position of the driving component on the valve is usually a dynamic sealing structure.

[0017] In order to realize the application of the planetary roller screw pair structure on the valve structure, the above structure is proposed. While utilizing the characteristics of the planetary roller screw pair structure itself to ensure the reliability of the valve and shorten the time required for opening and closing the valve, it can also optimize the problem of radiation material leakage of nuclear power valves, simplify the valve structure, and be beneficial to the radiation protection treatment of the valve after retirement.

[0018] Specifically, when the present scheme is used, the driving assembly can use a driving motor as a power source to directly or through a reducer drive the screw nut assembly to rotate. The screw nut assembly drives the planetary roller to move linearly along the axis of the screw, thereby causing the object connected thereto to move linearly. The object can be a valve plate, so as to change the state of the valve by the action of the valve plate.

[0019] Differences from the prior art:

[0020] Firstly, when the present scheme is used on a valve, the characteristics of the planetary roller screw itself are beneficial to the reliability of the valve opening and closing, the improvement of the valve structure stiffness, and the shortening of the valve action time.

[0021] Secondly, when the driving assembly is in action, the screw rod generates linear motion, so the valve plate can be directly connected to the screw rod, and since there is no push rod and other structures, the scheme has simple structure and fewer components, and when the scheme is applied to the upper valve of the primary loop of a nuclear reactor and used as a valve driving mechanism, the relatively simple structure is beneficial to the radiation protection treatment after the valve is decommissioned.

[0022] Finally, the sealing sleeve is used as the mounting seat of the screw nut assembly, and when the scheme is applied to the upper valve of the primary loop of a nuclear reactor, the end of the sealing sleeve that is not connected to the driving assembly is used for sealing connection with the valve seat, and the driving assembly is used as the end seal of the other end of the sealing sleeve, so that the driving assembly and the sealing sleeve form a boundary that encloses the primary loop fluid, and there is no dynamic seal structure on the boundary (such as the packing seal and the expansion ring seal in the traditional valve structure, which are more likely to cause seal failure compared to static seals, and the packing seal also greatly increases the movement resistance of the valve plate), and such a structure is beneficial to ensuring the reliability of the seal of the primary loop fluid, thereby being beneficial to optimizing the radiation material leakage of the nuclear power valve.

[0023] Meanwhile, the scheme provides a specific machining method for the planetary roller screw pair.

[0024] As a person skilled in the art, when applied to a gate valve, the object acted on is the valve plate, and to achieve the connection between the sealing sleeve and the valve seat, a connecting flange or a welding bevel can be arranged at the lower end of the sealing sleeve; the driving assembly can be arranged to include a driving motor and a small-volume planetary reducer, and the screw nut assembly is connected to the output end of the planetary reducer through a gear pair, or a driving motor directly drives the screw nut assembly, and in specific applications, the driving motor is installed in a closed housing or the driving motor and the planetary reducer are installed in a closed housing, and the housing is sealingly connected to the end of the sealing sleeve, and as a person skilled in the art, to achieve sealing connection, static sealing can be used at this position.

[0025] As a further technical scheme of the machining method for the planetary roller screw pair for nuclear power:

[0026] In the process of rotating the screw nut assembly and linearly moving the screw, the terminal position of the movement of the screw to the side where the driving assembly is located is outside the sealing sleeve. A stroke cavity for accommodating the screw is further arranged in the driving assembly, and the terminal position is located in the stroke cavity. The scheme aims to solve the following problems: if the end of the sealing sleeve for mounting the driving assembly is taken as the upper end, in order to ensure the structural stability and facilitate the transmission of rotation, the screw nut assembly is preferably arranged at the upper end of the sealing sleeve. In this structure, in order to ensure the stroke of the screw, a stroke cavity is arranged on the driving assembly to match the space requirement of the further upward movement of the screw. As a person skilled in the art, the above stroke cavity is a cavity structure located in the sealing boundary of the driving assembly and connected to the upper end of the sealing sleeve.

[0027] The sealing assembly is further arranged as an axial seal for the gap between the sealing sleeve and the screw;

[0028] The sealing assembly is fixed to the inner side of the sealing sleeve, and the planetary roller screw is located between the driving assembly and the sealing assembly on the axis of the sealing sleeve. The scheme aims to solve the following problems: when the planetary roller screw pair is used on a valve as a valve structural member, the sealed fluid will flow from the flow passage in the valve seat to the side where the driving assembly is located through the gap between the sealing sleeve and the screw. In order to facilitate disassembly, when the connection position of the driving assembly and the sealing sleeve adopts static sealing, there is a risk of leakage at this position. In order to reduce the possibility of leakage at this position or reduce the leakage amount when leakage occurs, the sealing assembly is further arranged as an axial seal for the gap between the sealing sleeve and the screw. In the application, the cavity on the side of the sealing assembly close to the valve plate is regarded as the front cavity, and the cavity on the side of the sealing assembly close to the driving assembly is regarded as the rear cavity. In this application, the sealing assembly does not need to completely prevent the fluid from entering the rear cavity from the front cavity. When leakage occurs at the connection between the driving assembly and the sealing sleeve, the sealing assembly plays a throttling role, which is beneficial to the leakage treatment and leakage amount control in the rear cavity. In specific implementation, the corresponding purpose can be achieved by controlling the gap between the sealing assembly and the screw. For example, the sealing assembly includes a sealing ring, the screw passes through the sealing ring, the inner wall of the sealing ring and the side wall of the screw that may contact the sealing ring are subjected to smooth treatment, the inner wall of the sealing ring and the outer wall surface of the screw are subjected to hardening treatment if necessary, the outer diameter of the screw is smaller than the inner diameter of the sealing ring, and the difference between the outer diameter and the inner diameter can be set to 0.05-0.2 mm according to the selected material.

[0029] The sealing assembly is a metal ring or a ceramic ring welded on the inner wall of the sealing sleeve;

[0030] In the assembly method, the screw rod is passed through the sealing assembly from the end where the screw nut assembly of the sealing assembly is located, and then the sealing assembly is welded under the constraint of the screw rod. The scheme aims to provide a scheme that is convenient to guarantee the coaxiality of the sealing assembly and the sealing sleeve and is convenient to install the sealing assembly. Specifically, when the scheme is applied to a gate valve, the sealing assembly is embedded in the sealing sleeve from the end of the sealing sleeve where the driving assembly is not arranged before the sealing sleeve is connected with the valve seat, and the positioning and coaxiality constraint of the sealing assembly are realized through the positioning step machined on the inner hole of the sealing sleeve, and then the welding is completed through the pipe opening of the sealing sleeve. The sealing assembly is arranged as a metal ring or a ceramic ring, which not only makes the scheme suitable for being applied to the valve on the primary loop of the nuclear reactor, but also makes the sealing assembly itself serve as a bearing bush. As to the further limitation that the welding is implemented after the sealing assembly is matched with the screw rod, the scheme aims to provide a technical scheme for guaranteeing the assembly precision of the sealing assembly after welding by using the screw rod.

[0031] The scheme also includes a heat tracing assembly for heat tracing the sealing sleeve and a temperature sensor for monitoring the temperature of the screw rod and the sealing sleeve. The scheme aims to solve the problem that when the scheme is applied to the valve on the primary loop of the nuclear reactor, the coolant in contact with the valve may have a temperature change of hundreds of degrees Celsius (such as 300℃), and without other temperature control interventions on the valve, the heat conduction will cause a large range of temperature changes of the scheme. Although the selection and parameter design of the sealing sleeve, the rolling bearing, the screw rod, and the screw nut assembly can optimize the matching precision between the parts (especially the matching precision of the screw rod and the screw nut assembly) at different temperatures to a certain extent, it is difficult to make the scheme have better part matching precision at each temperature in the temperature range of hundreds of degrees Celsius. Therefore, the above scheme is provided. In specific application, according to the selection and parameter design of the sealing sleeve, the rolling bearing, the screw rod, and the screw nut assembly, when the fluid in the valve is in a cold state, the sealing sleeve is heat traced by the heat tracing assembly to have a temperature higher than that of the primary loop fluid, and when the fluid in the valve is in a hot state, it is determined whether the sealing sleeve is heated by the heat tracing assembly according to the specific temperature, so as to reduce the size of the temperature change range of the planetary roller screw pair when the temperature of the primary loop fluid changes, and to guarantee the matching precision of the parts on the planetary roller screw pair by using the relatively constant range of the planetary roller screw pair, thereby achieving the purpose of further improving the reliability and service life of the planetary roller screw pair. As a person skilled in the art, the relatively simple way to heat the sealing sleeve by the heat tracing assembly is external heating, and the temperature sensor is further arranged to obtain the temperature and temperature difference of the sealing sleeve and the screw rod, and the heating power of the heat tracing assembly can be determined according to the temperature and temperature difference, so as to shorten the time required for the temperature of the screw rod to reach the temperature in the set temperature range when the primary loop fluid is in a cold state.

[0032] The heat tracing assembly comprises an electric heating unit wound outside the sealing sleeve, and further comprises a heat preservation layer wrapped outside the electric heating unit.

[0033] The machining method of the parts in the planetary roller screw comprises the following steps:

[0034] The screw rod is machined by sequentially performing heat treatment, outer circle grinding, single-thread turning, and single-thread grinding.

[0035] The planetary roller in the screw nut assembly is machined by first machining the tooth profile at both ends, and then performing heat treatment, outer circle grinding, thread turning, and thread grinding.

[0036] The outer sleeve is machined by sequentially performing heat treatment, inner hole grinding, inner thread turning, inner thread grinding, and planetary gear assembly. The present application provides a specific machining method for a planetary roller screw, and the specific objects involve a screw rod and a screw nut assembly, which comprises the following steps: during machining of the screw rod, the planetary roller, and the outer sleeve, the heat treatment comprises eliminating material defects and residual stress, so as to improve the dimensional stability of the machined parts; the outer circle grinding and thread grinding are used to determine the size of the blank before turning and the structural size of the part; during machining of the planetary roller, the tooth profile is machined first and then heat treated, so that the blank and the tooth profile can be heat treated at different stages of heat treatment, and the tooth profile is further machined by grinding, etc.

[0037] As a further technical solution of the machining method of the planetary roller screw pair for nuclear power:

[0038] During machining of the tooth profile at both ends of the planetary roller, a plurality of axial grooves are machined on the blank after preliminary heat treatment, which are annularly and uniformly distributed along the axial direction of the blank.

[0039] During thread turning, the thread formed on the planetary roller covers the full length of the planetary roller segment where the tooth profile is located. In the present application, the preliminary heat treatment eliminates stress on the blank and improves the machining performance of the blank during machining of the grooves. In this application, the heat treatment after machining of the tooth profile is used to further release machining stress and to perform wear-resistant heat treatment on the tooth profile; during thread turning, the full length of the spiral line covering the tooth profile is machined to facilitate machining of the planetary roller.

[0040] The planetary roller screw pair further comprises a valve plate and a valve seat.

[0041] In the assembly method:

[0042] The valve plate is connected to the end of the screw far from the driving assembly;

[0043] The end of the sealing sleeve far from the driving assembly is sealingly connected to the valve seat. As a person skilled in the art, the present application is a specific application of the planetary roller screw pair to the valve structure.

[0044] The present application also discloses a method for using a planetary roller screw pair for nuclear power, wherein the planetary roller screw pair is the planetary roller screw pair according to any one of the preceding application;

[0045] The method comprises: driving a subject to move linearly along the axis of the screw by using the planetary roller screw pair, wherein the subject is fixed to the end of the screw far from the driving assembly;

[0046] The output end of the driving assembly outputs rotary motion, and the outer sleeve is driven to rotate around the axis of the outer sleeve by the output end;

[0047] The outer sleeve drives the screw to move linearly along the axis of the screw by cooperating with the planetary roller. The method is a method for driving a subject to move linearly by using the planetary roller screw pair. In a specific application, the subject can be a valve plate or other subjects.

[0048] The present application also discloses a valve for nuclear power, which comprises a valve seat, a valve plate, and a driving mechanism for driving the valve plate to move linearly, wherein the driving mechanism is the planetary roller screw pair according to any one of the preceding application;

[0049] The valve plate is connected to the end of the screw far from the driving assembly;

[0050] The end of the sealing sleeve far from the driving assembly is sealingly connected to the valve seat. The present application is a specific application of the planetary roller screw pair to the valve, i.e. a valve with high reliability, short action execution time, friendly to the deactivation treatment of retired valves, and high sealing reliability of radioactive substances. Preferably, the valve is a gate valve.

[0051] The present application has the following advantages:

[0052] Firstly, when the present application is applied to the valve, the characteristics of the planetary roller screw itself are beneficial to the reliability of the opening and closing of the valve, the improvement of the structural stiffness of the valve, and the shortening of the action time of the valve.

[0053] Secondly, when the driving assembly is in action, the screw rod generates linear motion, so the valve plate can be directly connected to the screw rod. Since there is no push rod and other structures, the scheme has simple structure and fewer components. When the scheme is applied to the upper valve of the primary loop of a nuclear reactor and used as a valve driving mechanism, the relatively simple structure is beneficial to the radiation protection treatment after the valve is decommissioned.

[0054] Finally, the sealing sleeve is used as the mounting seat of the screw nut assembly. When the scheme is applied to the upper valve of the primary loop of a nuclear reactor, one end of the sealing sleeve, which is not connected to the driving assembly, is used for sealing connection with the valve seat, and the driving assembly is used as the end seal of the other end of the sealing sleeve. In this way, the driving assembly and the sealing sleeve form a boundary that encloses the primary loop fluid, and there is no dynamic seal structure on the boundary (such as the packing seal and the expanded ring seal in the traditional valve structure, which are more likely to cause seal failure compared to static seals, and the packing seal also greatly increases the movement resistance of the valve plate). Such a structure is beneficial to ensuring the reliability of the seal of the primary loop fluid, and thus the above structure is beneficial to optimizing the radiation material leakage of the valve for nuclear power.

[0055] Meanwhile, the scheme also provides a machining method and a use method of the key components of the planetary roller screw pair and a valve comprising the planetary roller screw pair. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 FIG. 1 is a partial cross-sectional view of one specific embodiment of the planetary roller screw pair for nuclear power according to the scheme;

[0057] Figure 2 FIG. 2 is a partial cross-sectional view of another specific embodiment of the planetary roller screw pair for nuclear power according to the scheme; Figure 1 The structure provided is based on the addition of a heat tracing assembly.

[0058] The reference numerals in the drawings are as follows: 1, sealing sleeve; 2, screw rod; 3, screw nut assembly; 4, driving assembly; 5, sealing assembly; 6, valve plate; 7, valve seat; 8, rolling bearing; 9, heat tracing assembly. DETAILED DESCRIPTION

[0059] The application will be further described in detail below in conjunction with the embodiments, but the application is not limited to the following embodiments:

[0060] Embodiment 1:

[0061] As Figure 1 and Figure 2As shown, a nuclear power planet roller screw pair processing method, the planet roller screw pair includes planet roller screw and drive assembly 4 for driving planet roller screw, the planet roller screw includes screw 2 and screw nut assembly 3, further includes sealing sleeve 1, the outer sleeve of screw nut assembly 3 is coaxially installed in sealing sleeve 1 by rolling bearing 8;

[0062] The action mode of the drive assembly 4 to the planet roller screw is that the output end of the drive assembly 4 is connected with the outer sleeve and drives the outer sleeve to rotate, and the rotation is the rotation of the outer sleeve around its axis;

[0063] The drive assembly 4 is connected at the end of the sealing sleeve 1, and the drive assembly 4 serves as the end sealing member of the sealing sleeve 1;

[0064] The screw 2 cooperates with the screw nut assembly 3;

[0065] The processing method includes the assembly method of the planet roller screw pair, specifically:

[0066] S1, complete the preparation of each component of the planet roller screw pair;

[0067] S2, complete the installation of the screw nut assembly 3 in the sealing sleeve 1 through the rolling bearing 8; the screw 2 is installed in cooperation with the screw nut assembly 3;

[0068] S3, complete the connection of the drive assembly 4 with the end of the sealing sleeve 2, and complete the connection between the output end of the drive assembly 4 and the screw nut assembly 3.

[0069] In the prior art, as provided in the technical solution of application No. CN201810726919.7, the planetary roller screw has the advantages of service life, load transmission and structural stability, and when used as a valve driving mechanism, the reliability of the valve can be effectively guaranteed and the valve cutoff time required in an emergency situation can be reduced. As a valve that changes the opening and closing state of the valve through linear motion, the rotary motion of the driving mechanism is usually converted into the linear motion of the valve plate 6. As provided in the technical solution of application No. CN201810726919.7, in order to enable the valve connected to the push rod joint to perform opening and closing actions, the action process is as follows: the servo motor rotates, the planetary carrier drives the roller screw 2 to rotate, the roller screw 2 drives the roller nut to move linearly along the axis of the roller screw 2, the push rod connected to the roller nut moves synchronously with the roller nut, and the opening and closing state of the valve connected to the push rod joint changes. In addition, when the planetary roller screw is used as a component part of other linear drivers, as provided in the technical solution of application No. CN201510548911.2, in order to obtain the linear motion of the object acted upon, the scheme adopted is still that the motor drives the screw 2, the screw 2 drives the planetary nut to move linearly along the sleeve (guide sleeve), and the push rod connected to the planetary nut acts on the object to be executed. In the structure provided by the above prior art, in addition to the structure of the planetary roller screw itself, a push rod is also included. At the same time, when the planetary roller screw is used to drive the valve to act, the push rod is connected to the valve plate 6, the space where the valve plate 6 is located is in communication with the fluid environment of the pipeline, and in order to avoid or reduce fluid leakage, a sealing structure is necessarily included in the structure, and the sealing structure at the position of the driving component on the valve is usually a dynamic sealing structure.

[0070] In order to realize the use of the planetary roller screw pair structure on the valve structure, the above structure is proposed in the present scheme, which not only utilizes the characteristics of the planetary roller screw pair structure itself to guarantee the reliability of the valve and shorten the time required for opening and closing the valve, but also optimizes the problem of leakage of radioactive substances of the valve for nuclear power, simplifies the structure of the valve, and is beneficial to the radiation protection treatment of the valve after retirement.

[0071] Specifically, when the present scheme is used, the driving assembly 4 can adopt a driving motor as a power source to directly or through a reducer drive the screw nut assembly 3 to rotate, the screw nut assembly 3 drives the planetary roller to drive the screw 2 to move linearly, so that the object connected thereto moves linearly, and the object can be the valve plate 6, so as to change the state of the valve by the action of the valve plate 6.

[0072] Differences from the prior art:

[0073] Firstly, when the present scheme is used on the valve, the characteristics of the planetary roller screw itself are beneficial to the reliability of the valve opening and closing, the improvement of the structural stiffness of the valve, and the shortening of the valve action time.

[0074] Secondly, when the driving assembly 4 is in action, the lead screw 2 generates linear motion, so the valve plate 6 can be directly connected to the lead screw 2, and since there is no push rod or the like structure, the scheme has simple structure and fewer components, and when the scheme is applied to the upper valve of the primary loop of a nuclear reactor and used as a valve driving mechanism, the relatively simple structure is beneficial to the radiation protection treatment after the valve is decommissioned.

[0075] Finally, the sealing sleeve 1 is used as the mounting seat of the lead screw nut assembly 3 in the scheme, and when the scheme is applied to the upper valve of the primary loop of a nuclear reactor, one end of the sealing sleeve 1 not connected with the driving assembly 4 is used for sealing connection with the valve seat 7, and the driving assembly 4 is used as the end seal of the other end of the sealing sleeve 1, so that the driving assembly 4 and the sealing sleeve 1 enclose a boundary of the primary loop fluid, and there is no dynamic seal structure on the boundary (such as the packing seal and the expanded ring seal in the traditional valve structure, which are more likely to cause seal failure compared with static seal, and the packing seal also greatly increases the movement resistance of the valve plate 6), and such a structure is beneficial to the reliability of the sealing of the primary loop fluid, thereby being beneficial to the optimization of the radiation material leakage of the valve for nuclear power.

[0076] As a person skilled in the art, when the scheme is applied to a gate valve, the object acted on is the valve plate 6, and to realize the connection between the sealing sleeve 1 and the valve seat 7, a connecting flange or a welding bevel can be arranged at the lower end of the sealing sleeve 1; the driving assembly 4 can be provided with a driving motor and a small-sized planetary reducer, and the lead screw nut assembly 3 is connected to the output end of the planetary reducer through a gear pair, or the driving motor directly drives the lead screw nut assembly 3, and in specific application, the driving motor is installed in a closed shell or the driving motor and the planetary reducer are installed in a closed shell, and the shell is sealingly connected with the end of the sealing sleeve 1, and as a person skilled in the art, static seal can be used for sealing at this position.

[0077] Embodiment 2:

[0078] The embodiment is further refined on the basis of Embodiment 1:

[0079] In the process of rotating the screw nut assembly 3 and linearly moving the screw 2, the terminal position of the movement of the screw 2 to the side where the driving assembly 4 is located is located outside the sealing sleeve 1, and the driving assembly 4 is further provided with a stroke cavity for accommodating the screw 2, and the terminal position is located in the stroke cavity. The scheme aims to solve the following problems: If the end of the sealing sleeve 1 for mounting the driving assembly 4 is taken as the upper end, in order to ensure the stability of the structure and facilitate the transmission of rotation, it is appropriate to arrange the screw nut assembly 3 at the upper end of the sealing sleeve 1. In this structure, in order to ensure the stroke of the screw 2, a stroke cavity is arranged on the driving assembly 4 to match the further upward movement of the screw 2 to the space requirement. As a person skilled in the art, the above stroke cavity is a cavity structure located in the sealing boundary of the driving assembly 4 and connected to the upper end of the sealing sleeve 1.

[0080] Embodiment 3:

[0081] This embodiment is further refined on the basis of embodiment 1:

[0082] Further comprising a sealing assembly 5, which is an axial seal between the sealing sleeve 1 and the screw 2;

[0083] The sealing assembly 5 is fixed to the inside of the sealing sleeve 1, and the planetary roller screw is located between the driving assembly 4 and the sealing assembly 5 on the axis of the sealing sleeve. The scheme aims to solve the following problems: When the planetary roller screw pair is used on the valve as a valve structural part, the sealed fluid will flow from the flow passage in the valve seat 7 to the side where the driving assembly 4 is located through the gap between the sealing sleeve 1 and the screw 2. In order to facilitate disassembly, when the connection position of the driving assembly 4 and the sealing sleeve 1 adopts static sealing, there is a risk of leakage at this position. In order to reduce the possibility of leakage at this position or reduce the leakage amount when leakage occurs, the sealing assembly 5 is arranged, which is an axial seal between the sealing sleeve 1 and the screw 2. If the cavity on the side close to the valve plate 6 of the sealing assembly 5 on the valve is regarded as the front cavity, and the cavity on the side close to the driving assembly 4 of the sealing assembly 5 is regarded as the rear cavity, in this application, the sealing assembly 5 does not need to completely prevent the fluid from entering the rear cavity from the front cavity. When leakage occurs at the connection between the driving assembly 4 and the sealing sleeve 1, the sealing assembly 5 plays a throttling role, which is beneficial to the leakage treatment and leakage amount control in the rear cavity. In specific implementation, the corresponding purpose can be achieved by controlling the gap between the sealing assembly 5 and the screw 2, such as arranging the sealing assembly 5 to include a sealing ring, the screw 2 passes through the sealing ring, the inner wall of the sealing ring and the side wall of the screw 2 that may contact the sealing ring are subjected to smooth treatment, and in the case of need, the inner wall of the sealing ring and the outer wall surface of the screw 2 are subjected to hardening treatment. The outer diameter of the screw 2 is smaller than the inner diameter of the sealing ring, and the difference between the outer diameter and the inner diameter can be set to 0.05-0.2 mm according to the material selection.

[0084] The sealing assembly 5 is a metal ring or a ceramic ring welded on the inner wall of the sealing sleeve 1;

[0085] In the assembly method, after the screw rod 2 is passed through the sealing assembly 5 from the end where the screw nut assembly 3 of the sealing assembly 5 is located, the sealing assembly 5 is welded under the constraint of the screw rod 2. The scheme is designed to provide a scheme which is convenient to guarantee the coaxiality of the sealing assembly 5 and the sealing sleeve 1 and convenient to install the sealing assembly 5. Specifically, when the scheme is applied to a gate valve, the sealing assembly 5 is embedded into the sealing sleeve 1 from the end of the sealing sleeve 1 where the driving assembly 4 is not arranged before the sealing sleeve 1 is connected with the valve seat 7, and the positioning and the coaxiality constraint of the sealing assembly 5 are realized through the positioning step machined on the inner hole of the sealing sleeve 1, and then the welding is completed through the pipe opening of the sealing sleeve 1. The sealing assembly 5 is arranged as a metal ring or a ceramic ring, which not only makes the scheme suitable for being applied to the valve on the primary loop of a nuclear reactor, but also makes the sealing assembly 5 itself serve as a bearing.

[0086] Embodiment 4:

[0087] The embodiment is further refined on the basis of Embodiment 1:

[0088] The heat tracing assembly 9 is further included for tracing the sealing sleeve 1, and the temperature sensor is further included for monitoring the temperature of the lead screw 2 and the sealing sleeve 1. The scheme aims to solve the problem that when the scheme is applied to the valve on the primary loop of the nuclear reactor, the coolant in contact with the valve may have a temperature change of hundreds of degrees Celsius (such as 300℃), and without other temperature control intervention on the valve, the scheme will have a large range of working temperature change under the action of heat conduction. Although the selection of materials and parameter design of the sealing sleeve 1, the rolling bearing 8, the lead screw 2 and the lead screw nut assembly 3 can optimize the matching precision between the parts at different temperatures to a certain extent (especially the matching precision of the lead screw 2 and the lead screw nut assembly 3), it is difficult to make the scheme have better part matching precision at each temperature in the temperature range of hundreds of degrees Celsius. Therefore, the above scheme is provided. In specific application, according to the selection of materials and parameter design of the sealing sleeve 1, the rolling bearing 8, the lead screw 2 and the lead screw nut assembly 3, when the fluid in the valve is in a cold state, the sealing sleeve 1 is heated by the heat tracing assembly 9, so that the sealing sleeve 1 has a temperature higher than that of the primary loop fluid. When the fluid in the valve is in a hot state, it is determined whether the heat tracing assembly 9 heats the sealing sleeve 1 according to the specific temperature, so as to reduce the size of the temperature change range of the planetary roller screw pair when the primary loop fluid temperature changes, and use the relatively constant range of the planetary roller screw pair to ensure the matching precision of the parts thereon, so as to further improve the reliability and service life of the planetary roller screw pair. As a person skilled in the art, a relatively simple way for the heat tracing assembly 9 to heat the sealing sleeve 1 is external heating. Further provided is that the heat tracing assembly 9 further includes a temperature sensor, which can be used to obtain the temperatures of the sealing sleeve 1 and the lead screw 2 and the temperature difference therebetween. According to the temperature and the temperature difference, the heating power of the heat tracing assembly 9 can be determined, so as to shorten the time required for the temperature of the lead screw 2 to reach the temperature in the set temperature range when the primary loop fluid is in a cold state.

[0089] The heat tracing assembly 9 includes an electric heating unit wound outside the sealing sleeve 1, and the heat tracing assembly 9 further includes a heat preservation layer wrapped outside the electric heating unit. The scheme provides a specific implementation form of the heat tracing assembly 9, which is to heat the sealing sleeve 1 by the electric heating unit and use the heat preservation layer to improve the heating efficiency of the heat tracing assembly 9 and reduce heat dissipation.

[0090] Embodiment 5:

[0091] The embodiment further refines the embodiment 1: the machining method of the parts in the planetary roller screw is:

[0092] The lead screw 2 is machined by sequentially performing heat treatment, external grinding, single-thread turning and single-thread grinding;

[0093] The planet roller in the screw nut assembly 3 is processed by first machining the tooth shape of two ends, then heat treatment, outer circle grinding, thread turning, and thread grinding to complete the processing;

[0094] The outer sleeve is processed by sequentially performing heat treatment, inner hole grinding, inner thread turning, inner thread grinding, and planet gear assembly. The present application provides a specific planet roller screw machining method, and the specific object relates to the screw 2 and the screw nut assembly 3, specifically: when machining the screw 2, the planet roller, and the outer sleeve, according to the material used, the heat treatment includes eliminating material organizational defects, eliminating residual stress, etc., thereby improving the dimensional stability of the machined parts; the outer circle grinding and thread grinding are used to determine the size of the blank before turning and the structure size on the part; during the planet roller machining process, the heat treatment is performed after the tooth shape is machined first, which can heat treat the blank and the tooth shape in different stages of heat treatment, and further finish machining such as gear grinding is performed on the tooth shape after heat treatment.

[0095] Embodiment 6:

[0096] This embodiment is further refined based on embodiment 5:

[0097] When machining the tooth shape of both ends of the planet roller, after the preliminary heat treatment of the blank, a plurality of axial grooves are machined on both ends of the blank along the axial direction of the blank and are evenly distributed around the blank axis;

[0098] When thread turning is performed, the thread formed on the planet roller covers the full length of the planet roller segment where the tooth shape is located. In this application, the preliminary heat treatment eliminates the stress on the blank and improves the machining performance of the blank during groove machining. In this application, the heat treatment after tooth shape machining is used to further release the machining stress and to perform wear-resistant heat treatment on the tooth shape; when thread turning is performed, the helical line covers the full length of the tooth shape part, which facilitates planet roller machining.

[0099] Embodiment 7:

[0100] This embodiment is based on embodiment 1 and provides a method for using a planet roller screw pair for nuclear power, wherein the planet roller screw pair is the planet roller screw pair described in embodiment 1;

[0101] The use method is: using the planet roller screw pair to drive the object to move linearly along the axial direction of the screw 2, and the object is fixed on the end of the screw 2 away from the driving assembly 4;

[0102] The output end of the driving assembly 4 outputs rotary motion, and drives the outer sleeve to rotate around the axis of the outer sleeve through the output end;

[0103] The outer sleeve drives the lead screw 2 via planetary rollers, causing the lead screw 2 to move linearly along its axis. This method describes how the planetary roller lead screw pair drives the linear motion of the object being acted upon. In specific applications, the object being acted upon can be the valve plate 6 or other objects.

[0104] Example 8:

[0105] Based on Embodiment 1, this embodiment provides a valve for nuclear power plants, including a valve seat 7, a valve plate 6, and a drive mechanism for driving the valve plate 6 to move linearly. The drive mechanism is the planetary roller screw pair described in Embodiment 1.

[0106] The valve plate 6 is connected to the end of the lead screw 2 away from the drive assembly 4;

[0107] The end of the sealing sleeve 1 furthest from the drive assembly 4 is sealed to the valve seat 7. This solution is a specific application of the planetary roller screw pair in a valve, providing a valve with high reliability, short action time, ease of post-decommissioning radiation protection, and high reliability in sealing against radioactive materials. Preferably, this valve is a gate valve.

[0108] Example 9:

[0109] This embodiment is a further refinement of embodiment 1:

[0110] It also includes valve plate 6 and valve seat 7;

[0111] In the assembly method:

[0112] Connect the valve plate 6 to the end of the lead screw 2 away from the drive assembly 4;

[0113] The end of the sealing sleeve 1 away from the drive assembly 4 is sealed to the valve seat 7.

[0114] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, other embodiments derived without departing from the technical solution of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for machining a planetary roller screw pair for nuclear power plants, the planetary roller screw pair comprising a planetary roller screw and a drive assembly (4) for driving the planetary roller screw, the planetary roller screw comprising a screw (2) and a screw nut assembly (3), characterized in that, It also includes a sealing sleeve (1), and the outer sleeve of the lead screw nut assembly (3) is coaxially installed in the sealing sleeve (1) via a rolling bearing (8); The driving component (4) acts on the planetary roller screw in the following way: the output end of the driving component (4) is connected to the outer sleeve and drives the outer sleeve to rotate, the rotation being the outer sleeve rotating around its own axis; The drive assembly (4) is connected to the end of the sealing sleeve (1), and the drive assembly (4) serves as the end seal of the sealing sleeve (1); the connection between the drive assembly (4) and the sealing sleeve (1) is statically sealed. The lead screw (2) is engaged with the lead screw nut assembly (3); The processing method includes the assembly method of the planetary roller screw pair, specifically: S1. Complete the preparation of all components of the planetary roller screw pair. S2. The screw nut assembly (3) is installed in the sealing sleeve (1) by means of the rolling bearing (8); the screw (2) and the screw nut assembly (3) are installed together. S3. Complete the connection between the drive assembly (4) and the end of the sealing sleeve (1), and complete the connection between the output end of the drive assembly (4) and the lead screw nut assembly (3); It also includes a sealing assembly (5), which serves as an axial seal for the gap between the sealing sleeve (1) and the lead screw (2); The sealing assembly (5) is fixed to the inner side of the sealing sleeve (1), and the planetary roller screw is located between the drive assembly (4) and the sealing assembly (5) on the axis of the sealing sleeve (1). The sealing assembly (5) includes a sealing ring, and a lead screw (2) passes through the sealing ring. The outer diameter of the lead screw (2) is smaller than the inner diameter of the sealing ring, and the difference between the outer diameter and the inner diameter is 0.05~0.2mm. It also includes a heat tracing assembly (9) for heat tracing the sealing sleeve (1).

2. The method for machining a planetary roller screw pair for nuclear power plants according to claim 1, characterized in that, During the rotation of the lead screw nut assembly (3) and the linear motion of the lead screw (2), the end point of the lead screw (2) moving towards the side of the drive assembly (4) is located outside the sealing sleeve (1). The drive assembly (4) is also provided with a stroke cavity for accommodating the lead screw (2), and the end point is located in the stroke cavity.

3. The method for machining a planetary roller screw pair for nuclear power plants according to claim 1, characterized in that, The sealing component (5) is a metal ring or ceramic ring welded to the inner wall of the sealing sleeve (1); In the assembly method, after the lead screw (2) passes through the sealing assembly (5) from the end where the lead screw nut assembly (3) of the sealing assembly (5) is located, the sealing assembly (5) is welded under the constraint of the lead screw (2).

4. The method for machining a planetary roller screw pair for nuclear power plants according to claim 1, characterized in that, It also includes a temperature sensor for monitoring the temperature of the lead screw (2) and the sealing sleeve (1).

5. A method for machining a planetary roller screw pair for nuclear power plants according to claim 1, characterized in that, The heat tracing assembly (9) includes an electric heating unit wrapped around the outside of the sealing sleeve (1), and the heat tracing assembly (9) also includes an insulation layer covering the outside of the electric heating unit.

6. The method for machining a planetary roller screw pair for nuclear power plants according to claim 1, characterized in that, The machining method for the components in the planetary roller screw is as follows: The lead screw (2) is processed by heat treatment, outer circle grinding, single-start thread turning, and single-start thread grinding in sequence; The planetary rollers in the lead screw nut assembly (3) are first machined with the tooth profiles at both ends, and then heat-treated, ground on the outer circle, threaded turning, and threaded grinding to complete the machining process. The outer casing is processed by sequential heat treatment, internal hole grinding, internal thread turning, internal thread grinding and forming, and planetary gear ring assembly.

7. A method for machining a planetary roller screw pair for nuclear power plants according to claim 6, characterized in that, When machining the tooth profile at both ends of the planetary roller, after the blank is subjected to preliminary heat treatment, multiple axial grooves are machined at both ends of the blank along the axial direction of the blank and evenly distributed in a ring relative to the blank axis. During thread turning, the thread formed on the planetary roller covers the entire length of the planetary roller section containing the tooth profile.

8. A method for machining a planetary roller screw pair for nuclear power plants according to claim 1, characterized in that, The planetary roller screw pair also includes a valve plate (6) and a valve seat (7); In the assembly method: Connect the valve plate (6) to the end of the lead screw (2) away from the drive assembly (4); The end of the sealing sleeve (1) away from the drive assembly (4) is sealed to the valve seat (7).

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