Method and device for assembling large nuclear valves

Abstract

The application discloses an assembling method and an assembling device for a large nuclear valve. The connecting part of the tension bolt is protected when the tension bolt with reverse first threads and second threads is assembled with the piston and the valve cover of the large nuclear valve. The assembling method comprises the following steps: a piston connecting step: the piston is lifted by a lifting mechanism and placed on a supporting mechanism, and at least part of the first threads of the lower end of the tension bolt is screwed into the first thread hole of the upper end of the piston; a measuring step: the tension bolt is measured to obtain the first length of the first threads screwed into the first thread hole; a tension bolt fixing step: the tension bolt is inserted into the piston from the bottom of the piston by a lifting mechanism arranged in the supporting mechanism; and a valve cover connecting step: the valve cover is lifted by the lifting mechanism, the second thread hole of the lower end of the valve cover is kept fixed on the tension bolt, and at least part of the second threads is screwed into the second thread hole according to the first length.

Description

Technical Field

[0001] This invention relates to the field of valve assembly technology, and more specifically to an assembly method and assembly apparatus for the overall assembly of large AP1000 nuclear-grade valves. Background Technology

[0002] The AP1000 rupture valve is one of the six critical components of a nuclear power plant, serving as the last line of defense for plant safety. This valve employs a blast-activated mechanism, and its main components include a cartridge case, valve body, piston, shear cap, and tension bolt. The valve cap and piston are connected by a tension bolt, which has threads in opposite directions at both ends and an annular shear groove at the center. One threaded end screws into the central blind hole of the valve cap, while the other threaded end screws into the threaded hole of the piston. The valve opens by shearing through the tension bolt's shear groove; therefore, the tension bolt's shear groove is a crucial component. Care must be taken during valve assembly to avoid damaging or twisting the tension bolt's shear groove. In the early stages of product development, without dedicated tooling, installation was carried out using a crane and personnel with simple lifting equipment. Common problems during installation included improper thread installation, significant misalignment between workpieces, and a mismatch between the valve cover's descent and the distance it traveled when engaging the tension bolt during rotation. This mismatch caused the valve cover's weight to press on the tension bolt or exert tension on it, both of which acted on the shear groove of the tension bolt, damaging it and affecting valve quality. Furthermore, engaging the tension bolt with the piston required inserting a wrench from below, posing a challenge for operators. Therefore, protecting the shear groove of the tension bolt during assembly became a pressing issue.

[0003] Therefore, there is an urgent need to develop an assembly method and assembly device for large nuclear valves that overcomes the above-mentioned defects. Summary of the Invention

[0004] To address the above problems, the present invention provides an assembly method for a large nuclear valve, wherein, when assembling a tension bolt having a first reverse thread and a second reverse thread with the piston and valve cover of the large nuclear valve using the assembly method, the tension bolt shear groove on the tension bolt is protected. The assembly method includes:

[0005] Piston connection steps: After the piston is lifted by the lifting mechanism, it is placed on a support mechanism, and at least a portion of the first thread at the lower end of the tension bolt is screwed into the first threaded hole at the upper end of the piston;

[0006] Measurement steps: Measure the tension bolt to obtain the first length of the first thread screwed into the first threaded hole;

[0007] Tension bolt fixing steps: A lifting mechanism installed in the support mechanism extends from the bottom of the piston to fix the lower end of the tension bolt;

[0008] Valve cover connection steps: After the valve cover is lifted by the lifting mechanism so that the second threaded hole at the lower end of the valve cover is fixed to the upper end of the tension bolt, the valve cover is rotated according to the first length to screw at least a portion of the second thread into the second threaded hole.

[0009] The above assembly method, wherein the piston connection step includes:

[0010] A bracket is set horizontally, and a limiting plate is lifted by the lifting mechanism so that the first limiting hole on the limiting plate aligns with the second limiting hole on the bracket. Then the limiting plate is placed on the bracket.

[0011] The limiting plate is fixed to the bracket by means of limiting pins passing through the first limiting hole and the second limiting hole;

[0012] The piston is lifted by the lifting mechanism so that the lower end of the piston is aligned with the mounting hole on the limiting plate. Then, the lower end of the piston is inserted into the mounting hole and extends into the bracket, while the upper end of the piston is located on the limiting plate.

[0013] The lower end of the tension bolt is screwed into the first threaded hole from above the piston through the first thread.

[0014] The assembly method described above, wherein the tension bolt fixing step includes:

[0015] A connector extends from the connecting hole at the lower end of the piston and connects to the lower end of the tension bolt;

[0016] The lower end of the tension bolt is fixed in the first threaded hole by pushing the connector against a height adjustment component mounted on the bracket.

[0017] The above-described assembly method, wherein the step of fixing the lower end of the tension bolt into the first threaded hole by pushing the connector against a height adjustment component mounted on the bracket includes:

[0018] The connecting pipe with opposite third and fourth threads at both ends is assembled and connected to the first and second columns respectively through the third thread and the third thread.

[0019] Install the support block on the second column;

[0020] The first column is mounted on the bracket using a support assembly;

[0021] Rotating the connecting pipe raises the support block to push against the connecting piece.

[0022] The assembly method described above, wherein the valve cover connection step includes: rotating the valve cover according to the first length to screw the second length of the second thread into the second threaded hole, wherein the first length is the same as the second length.

[0023] The present invention also provides an assembly apparatus for a large nuclear valve, wherein, when assembling a tension bolt having a first reverse thread and a second reverse thread with the piston and valve cover of the large nuclear valve using the assembly apparatus, the tension bolt shear groove on the tension bolt is protected. The assembly apparatus includes:

[0024] The piston is lifted and placed on the support mechanism by a lifting mechanism, and at least a portion of the first thread at the lower end of the tension bolt is screwed into the first threaded hole at the upper end of the piston.

[0025] A lifting mechanism is installed on the support mechanism. The lifting mechanism extends from the bottom of the piston into the piston to fix and support the lower end of the tension bolt. The lifting mechanism lifts the valve cover so that the second threaded hole at the lower end of the valve cover is fixed to the upper end of the tension bolt. The valve cover is then rotated according to the measured first length to screw at least a portion of the second thread into the second threaded hole.

[0026] Wherein, the first length is the length of the first thread screwed into the first threaded hole.

[0027] The aforementioned assembly device, wherein the support mechanism includes:

[0028] A limiting plate, wherein a mounting hole is provided in the middle for the lower end of the piston to pass through and at least one first limiting hole is provided around the mounting hole;

[0029] A bracket has a top plate, on which a through hole is provided for the lower end of the piston to pass through and at least one second limiting hole is provided around the through hole. A limiting plate is mounted on the top plate, and the mounting hole is located at the through hole, and the first limiting hole is located at the second limiting hole.

[0030] A limiting pin is inserted through the first limiting hole and the second limiting hole to fix the limiting plate to the top plate;

[0031] The piston is placed on the limiting plate, the lower end of the piston extends into the bracket through the mounting hole and the through hole, and the upper end of the piston is located on the limiting plate.

[0032] The aforementioned assembly device, wherein the bracket further comprises multiple support legs connected to the top plate, and the lifting mechanism includes:

[0033] A connector, one end of which extends into the piston from the connecting hole at the lower end of the piston and is connected to the lower end of the tension bolt;

[0034] The height adjustment component is mounted on the support leg via the support component. The height adjustment component adjusts its own height to push against the other end of the connector, thereby fixing the lower end of the tension bolt into the first threaded hole.

[0035] The aforementioned assembly device, wherein the height adjustment component includes:

[0036] The connecting pipe has opposite third and fourth threads on the inner walls at both ends;

[0037] The first column has one end inserted into one end of the connecting pipe and connected to the third thread, and the other end of the first column is connected to the support assembly;

[0038] The second column has one end extending into the other end of the connecting pipe and connected to the fourth thread;

[0039] A support block is installed on the other end of the second column;

[0040] In this method, rotating the connecting pipe causes the support block to rise and push against the other end of the connector.

[0041] The aforementioned assembly device, wherein the support assembly includes:

[0042] A support plate, with the other end of the first column mounted on the support plate;

[0043] Multiple inclined support members, one end of which is connected to the support plate, and the other end of which is correspondingly connected to multiple support legs.

[0044] The advantages of this invention compared to the prior art are as follows: This invention solves the problem that in the assembly process of large, high-end, and precision valves, the material size is too large and the weight is too heavy, which makes it easy for critical parts to be damaged due to force majeure, affecting the stability of valve quality and service life. This invention improves the installation quality of the valve, thereby improving the reliability of the valve during operation, while reducing safety risks.

[0045] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a flowchart of the assembly method of the present invention;

[0048] Figure 2 This is a schematic diagram of the assembly device of the present invention;

[0049] Figure 3 This is a plan view of the assembly device of the present invention;

[0050] Figure 4 This is a schematic diagram of the limiting plate.

[0051] Figure 5 This is a schematic diagram of the support structure;

[0052] Figure 6 This is a schematic diagram of the lifting mechanism;

[0053] Figure 7 This is a structural schematic diagram of the lifting mechanism;

[0054] Figure 8 This is a schematic diagram of a tension bolt.

[0055] Figure 9 This is a schematic diagram of the connecting pipe. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] The illustrative embodiments and descriptions of the present invention are used to explain the invention, but are not intended to limit the invention. Furthermore, elements / components using the same or similar reference numerals in the drawings and embodiments are used to represent the same or similar parts.

[0058] The terms "first," "second," "S1," "S2," etc., used in this document do not specifically refer to any order or sequence, nor are they intended to limit the invention. They are merely used to distinguish elements or operations described using the same technical terms.

[0059] The directional terms used in this article, such as up, down, left, right, front, or back, are for reference only when referring to the accompanying drawings. Therefore, the use of directional terms is for illustrative purposes and not to limit this work.

[0060] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0061] The term "and / or" as used herein includes any or all of the things mentioned.

[0062] The term "multiple" in this article includes "two" and "more than two"; the term "multiple groups" in this article includes "two groups" and "more than two groups".

[0063] Certain terms used to describe this application will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the application.

[0064] Please see Figures 1-2 , Figure 8 , Figure 1 This is a flowchart of the assembly method of the present invention; Figure 2 This is a schematic diagram of the assembly device of the present invention. Figure 8 This is a structural schematic diagram of a tension bolt. (Example:) Figures 1-2 , Figure 8 As shown, an assembly method for a large nuclear valve according to the present invention involves assembling a tension bolt 1 with a reverse first thread ST1 and a second thread ST2 to a piston 2 and a valve cover 3 of a large nuclear valve. The tension bolt shear groove 13 on the tension bolt 1 is protected. The assembly method includes:

[0065] Piston connection step S1: After the piston is lifted by the lifting mechanism 41, it is placed on a support mechanism 42, and at least a portion of the first thread ST1 at the lower end of the tension bolt 1 is screwed into the first threaded hole 21 at the upper end of the piston 2.

[0066] Measurement step S2: Measure the tension bolt 1 to obtain the first length of the first thread ST1 screwed into the first threaded hole 21;

[0067] Step S3 for fixing the tension bolt: A lifting mechanism 43 installed in the support mechanism 42 extends from the bottom of the piston 2 to fix the lower end of the tension bolt 1.

[0068] Valve cover connection step S4: After the valve cover 3 is lifted by the lifting mechanism 41 so that the second thread 31 hole at the lower end of the valve cover 3 is fixed to the upper end of the tension bolt 1, the valve cover 3 is rotated according to the first length so that at least part of the second thread ST2 is screwed into the second thread hole 31.

[0069] Furthermore, the piston connection step S1 includes:

[0070] A bracket 421 is set horizontally, and a limiting plate 422 is lifted by the lifting mechanism 41 so that the first limiting hole K1 on the limiting plate 422 is aligned with the second limiting hole K2 on the bracket 421, and then the limiting plate 422 is placed on the bracket 421.

[0071] The limiting plate 422 is fixed to the bracket 421 by means of the limiting pin 423 passing through the first limiting hole K1 and the second limiting hole K2;

[0072] The piston 2 is lifted by the lifting mechanism 41 so that the lower end of the piston 2 is aligned with the mounting hole K3 on the limiting plate 422. The lower end of the piston 2 is then inserted into the mounting hole K3 and extends into the bracket 421, while the upper end of the piston 2 is located on the limiting plate 422.

[0073] The lower end of the tension bolt 1 is screwed into the first threaded hole 21 from above the piston 2 through the first thread ST1.

[0074] Furthermore, the tension bolt fixing step S3 includes:

[0075] A connector 431 extends from the connecting hole K4 at the lower end of the piston 2 and connects to the lower end of the tension bolt 1;

[0076] The lower end of the tension bolt 1 is fixed in the first threaded hole 11 by pushing the connector 431 against a height adjustment component 432 mounted on the bracket 421.

[0077] The step of fixing the lower end of the tension bolt into the first threaded hole by pushing the connector against a height adjustment component mounted on the bracket includes:

[0078] The connecting pipe 4321, which has opposite third threads ST3 and fourth threads ST4 at both ends, is assembled and connected to the first column 4322 and the second column 4323 respectively through the third threads ST3 and ST4.

[0079] The support block 4324 is installed on the second column 4323;

[0080] The first column 4322 is mounted on the bracket 421 via the support assembly 433;

[0081] By rotating the connecting pipe 4321, the support block 4324 is raised to push against the connector 431.

[0082] Furthermore, the valve cover connection step S4 includes: rotating the valve cover 3 according to the first length to screw the second length of the second thread ST2 into the second threaded hole 31, wherein the first length is the same as the second length.

[0083] Please refer to the following: Figures 2-3 , Figure 3 This is a plan view of the assembly device of the present invention. Figures 2-3 As shown, an assembly device for a large nuclear valve according to the present invention protects the tension bolt shear groove 13 on the tension bolt 1 when assembling a tension bolt 1 with a reverse first thread ST1 and a second thread ST2 to a piston 2 and a valve cover 3 of a large nuclear valve.

[0084] Specifically, the tension bolt 1 has a first thread ST1 and a second thread ST2 in opposite directions at both ends, and has a smaller diameter connecting part 14 and a tension bolt shear groove 13 surrounding the connecting part 14 in the middle part. Figure 8 (As shown). One end of the tension bolt 1 is screwed into the second threaded hole 31 in the middle of the end face of the valve cover 3, and the other end is screwed into the first threaded hole 21 in the middle of the piston 2.

[0085] The assembly device includes a support mechanism 42 and a lifting mechanism 43. The support mechanism 42 lifts the piston 2 and places it on the support mechanism 42 after lifting it with a hoisting mechanism 41. At least a portion of the first thread ST1 at the lower end of the tension bolt 1 is screwed into the first threaded hole 21 at the upper end of the piston 2. The lifting mechanism 43 is mounted on the support mechanism 42. After the lifting mechanism 43 extends into the piston 2 from the bottom of the piston 2 to fix and support the lower end of the tension bolt 1, the valve cover 3 is lifted by the hoisting mechanism 41 so that the second threaded hole 31 at the lower end of the valve cover 3 is fixed to the upper end of the tension bolt 1. The valve cover 3 is rotated according to a measured first length to screw at least a portion of the second thread ST2 into the second threaded hole 31. The first length is the length of the first thread ST1 screwed into the first threaded hole 21.

[0086] Please refer to Figures 4-5 , Figure 4 This is a schematic diagram of the limiting plate. Figure 5 This is a schematic diagram of the support structure. (Example) Figures 4-5 As shown, and please refer to Figure 2 , Figure 3 and Figure 8 The support mechanism 42 includes: a limiting plate 422, a bracket 421, and a limiting pin 423. The limiting plate 422 has a mounting hole K3 in its center for the lower end of the piston 2 to pass through, and at least one first limiting hole K1 surrounding the mounting hole K3. The bracket 421 has a top plate 4211, on which a through hole K5 for the lower end of the piston to pass through is provided, and at least one second limiting hole K2 surrounding the through hole K5. The limiting plate 422 is mounted on the top plate 4211. Mounting hole K3 is located on the through hole K5, and the first limiting hole K1 is located on the second limiting hole K2; limiting pin 423 passes through the first limiting hole K1 and the second limiting hole K2 to fix the limiting plate 422 on the top plate 4211; wherein, the piston 2 is placed on the limiting plate 422, the lower end D1 of the piston 2 passes through the mounting hole K3 and the through hole K5 and extends into the bracket 421, and the upper end of the piston 2 is located on the limiting plate 422.

[0087] The bracket 421 is welded together with an upper flat plate (top plate) and a lower square tube (support leg). The upper square flat plate has a large circular through hole K5 in the center, and a circular second limiting hole K2 is provided around the through hole K5. The limiting plate 422 is a circular thick steel plate with a rectangular through hole K3 in the center and a first limiting hole K1 on its end face. The limiting plate 422 is placed on the bracket 4211, the first limiting hole K1 and the second limiting hole K2 are aligned, and the limiting pin 423 is inserted into the first limiting hole K1 and the second limiting hole K2. The lower flat part of the piston 2 is inserted into the mounting hole K3 and the through hole K5, and the upper part of the piston 2 is placed on the limiting plate 422.

[0088] Please refer to Figure 6 , Figure 6 This is a structural diagram of the lifting mechanism. Figure 6 As shown, and please refer to Figure 2 , Figure 3 and Figure 8 The bracket 421 also has a plurality of support legs 4212 connected to the top plate 4211. The lifting mechanism 43 includes: a connector 431, a height adjustment component 432 and a support component 433. One end of the connector 431 extends into the piston 2 from the connection hole K4 at the lower end of the piston 2 and is connected to the lower end of the tension bolt 1. The height adjustment component 432 is mounted on the support leg 4212 through the support component 433. The height adjustment component 432 adjusts its own height to push against the other end of the connector 431 to fix the lower end of the tension bolt 1 in the first threaded hole 21.

[0089] In this embodiment, the connector 431 is a hex wrench. The hex wrench is inserted from the connecting hole K4 in the middle of the lower end of the piston 2 into the hexagonal hole at the lower end of the tension bolt 1 screwed into the piston 2. By rotating the hex wrench, the length of the first thread ST1 of the tension bolt 1 screwed into the piston 2 can be adjusted to ensure that the tension bolt 1 is screwed into the inner cavity of the piston 2 at a suitable height. The lower end of the hex wrench is placed on the support block 4324.

[0090] Please refer to the following: Figure 9 , Figure 9This is a schematic diagram of the connecting pipe. The height adjustment assembly 432 includes: a connecting pipe 4321, a first column 4322, a second column 4323, and a support block 4324. The inner walls of both ends of the connecting pipe 4321 have opposite third threads ST3 and fourth threads ST4. One end of the first column 4322 extends into one end of the connecting pipe 4321 and is connected to the third thread ST3, and the other end of the first column 4322 is connected to the support assembly 433. One end of the second column 4323 extends into the other end of the connecting pipe 4321 and is connected to the fourth thread ST4. The support block 4324 is mounted on the other end of the second column 4323. By rotating the connecting pipe 4321, the support block 4324 is raised to push against the other end of the connecting pipe 431.

[0091] In this embodiment, a window W is provided on the side wall of the connecting pipe 4321. During installation, the third thread ST3 and the fourth thread ST4 can be observed through the window W to prevent the third thread ST3 and the fourth thread ST4 from being connected to the first column 4322 and the second column 4323 in a mismatch.

[0092] Therefore, a rotating support wrench with left and right bolts is mainly used to eliminate the operational difficulties caused to the operator by the downward gravity of the wrench during assembly. The workpiece placed at the lower end of piston 2 mainly fixes the piston. The tension bolt 1 is rotated into the inner cavity from the upper end of piston 2. The wrench is inserted from the center hole at the lower end of piston 2 and placed in the hexagonal hole on the end face of tension bolt 1. The tension bolt 1 is rotated and installed. The support block 4324 at the lower part of the wrench uses a connecting pipe 4321 with opposite internal threads to engage with the second column 4323 with left-hand threads and the first column 4322 with right-hand threads. The support block 4324 and the connecting piece 431 can be raised and lowered freely, thereby fixing the tension bolt 1 and keeping it fixed when the tension bolt 1 is screwed onto the valve cover 3.

[0093] In this embodiment, a connecting groove C is provided on one end face of the support block 4324. The support block 4324 is fixed to the second column 4323 by a screw 4325 passing through the bottom of the connecting groove C and the other end of the second column 4323. The connecting member 431 is pushed against the side wall of the connecting groove C.

[0094] The support component 433 includes a support plate 4331 and a plurality of inclined support members 4332. The other end of the first column 4322 is installed on the mounting hole K6 of the support plate 4331. One end of the plurality of inclined support members 4332 is connected to the support plate 4331, and the other end is correspondingly connected to a plurality of support legs 4212.

[0095] In this embodiment, the support component 433 may further include four horizontal supports 4333, each horizontal support 4333 having two or more support legs 4212 connected to both ends, and the other ends of two inclined support members 4332 being connected to two oppositely arranged horizontal supports 4333, with one end of each inclined support member 4332 being connected to a support plate 4331. The lower end of the support block 4324 is connected to a second column 4323 with a left-hand thread; two diagonal supports 4332 are welded to the horizontal support 4333 in the middle of the support leg 4212, and the support plate 4331 is welded to the upper end of the diagonal support 4332. The lower end of the first column 4322 with a right-hand thread passes through the mounting hole K6 of the support plate 4331, and the nut 4334 is threadedly connected to the first column 4322; one end of the connecting pipe 4321 has a left-hand thread, i.e., the third thread ST3, and the other end of the connecting pipe 4321 has a right-hand thread, i.e., the fourth thread ST4. One end of the connecting pipe 4321 is connected to the right-hand thread of the first column 4322, and the other end of the connecting pipe 4321 is connected to the left-hand thread of the second column 4323.

[0096] By rotating the same distance using the same thread, the movement of the mounting component is ensured to be smooth and reliable during installation. The thread guides the component, minimizing any swaying during installation and ensuring that the weight of the valve cover does not exert pressure or tension on the tension bolt, nor does it create tension or pressure on the shear groove. Simultaneously, the engagement of the tension bolt provides a guiding effect on the valve cover, preventing it from tilting during rotation and protecting the shear groove from damage caused by tilting torque. This ensures the quality of the tension bolt during assembly.

[0097] Please refer to Figure 7 , Figure 7 This is a structural diagram of the lifting mechanism. (Example) Figure 7 As shown, the assembly device of the present invention also includes a lifting mechanism 41. The lifting mechanism 41 includes a lifting rod 411 and a lifting seat 412. The lifting seat 412 is installed under the lifting rod 411 and is connected to the lifting rod 411 by a thread. There are three triangular reinforcing ribs around the lifting seat 412. The shackle 413 passes through the through hole on the surface of the reinforcing rib and is connected to the lifting seat 412. The lifting ring 414 is connected to the shackle 413 by a steel wire rope 415. The lifting ring 414 is used to connect with the object being lifted.

[0098] The following combination Figure 2 The working process of the assembly device of the present invention is described in detail below:

[0099] 1. Place bracket 421 flat on a level ground, lift and place the limiting plate 422 on the upper surface of bracket 421 and align it with the limiting hole, insert the limiting pin 423 into the limiting holes K1 and K2; lift piston 2, insert the flat part into the limiting plate 422 and place it on the upper end of the limiting plate 422; screw the tension bolt 1 (with an internal hexagonal end on the end face) into the inner hole of piston 3;

[0100] 2. Insert the connector 431 into the center hole at the lower end of the piston 2, connect the tension bolt 1, rotate the connecting pipe 4321, raise the support block 4324 and lift the connector 431;

[0101] 3. Lift the valve cover 3 and move it above the piston 2; align the threaded hole 31 at the lower end of the valve cover 3 with the external thread ST2 at the upper end of the tension bolt 1, and fix the lifting rod so that it cannot be rotated;

[0102] 4. Fix the connecting piece 431, rotate the valve cover 3 to move it downwards, and as the valve cover 3 moves, the tension bolt 1 is screwed into the threaded hole 31 at the lower end of the valve cover 3 until the lower end face of the valve cover 3 is in contact with the upper surface of the piston 2.

[0103] In summary, this invention solves the problem that in the assembly of large, high-end, and precision valves, the material dimensions are too large and the weight is too heavy, making critical parts susceptible to damage due to uncontrollable human factors, which affects the stability of valve quality and service life. This improves the installation quality of the valve, thereby increasing the reliability of the valve during operation and reducing safety risks.

[0104] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An assembly method for large nuclear valves, characterized in that, When assembling a tension bolt with reverse first and second threads to the piston and valve cover of a large nuclear valve using the assembly method described above, the connecting portion on the tension bolt is protected. The assembly method includes: Piston connection steps: After the piston is lifted by the lifting mechanism, it is placed on a support mechanism, and at least a portion of the first thread at the lower end of the tension bolt is screwed into the first threaded hole at the upper end of the piston; Measurement steps: Measure the tension bolt to obtain the first length of the first thread screwed into the first threaded hole; Tension bolt fixing steps: A lifting mechanism installed in the support mechanism extends from the bottom of the piston to fix the lower end of the tension bolt; Valve cover connection steps: After the valve cover is lifted by the lifting mechanism so that the second threaded hole at the lower end of the valve cover is fixed to the upper end of the tension bolt, the valve cover is rotated according to the first length to screw at least a portion of the second thread into the second threaded hole; The piston connection step includes: A bracket is set horizontally, and a limiting plate is lifted by the lifting mechanism so that the first limiting hole on the limiting plate aligns with the second limiting hole on the bracket. Then the limiting plate is placed on the bracket. The limiting plate is fixed to the bracket by means of limiting pins passing through the first limiting hole and the second limiting hole; The piston is lifted by the lifting mechanism so that the lower end of the piston is aligned with the mounting hole on the limiting plate. Then, the lower end of the piston is inserted into the mounting hole and extends into the bracket, while the upper end of the piston is located on the limiting plate. The lower end of the tension bolt is screwed into the first threaded hole from above the piston through the first thread.

2. The assembly method as described in claim 1, characterized in that, The tension bolt fixing steps include: A connector extends from the connecting hole at the lower end of the piston and connects to the lower end of the tension bolt; The lower end of the tension bolt is fixed in the first threaded hole by pushing the connector against a height adjustment component mounted on the bracket.

3. The assembly method as described in claim 2, characterized in that, The step of fixing the lower end of the tension bolt into the first threaded hole by pushing the connector against a height adjustment component mounted on the bracket includes: The connecting pipe with opposite third and fourth threads at both ends is assembled and connected to the first and second columns respectively through the third thread and the third thread. Install the support block on the second column; The first column is mounted on the bracket using a support assembly; Rotating the connecting pipe raises the support block to push against the connecting piece.

4. The assembly method as described in claim 2, characterized in that, The valve cover connection step includes: rotating the valve cover according to the first length to screw the second length of the second thread into the second threaded hole, wherein the first length is the same as the second length.

5. An assembly apparatus for large nuclear valves, characterized in that, When assembling a tension bolt with reverse first and second threads to the piston and valve cover of a large nuclear valve using the assembly device, the connection portion on the tension bolt is protected. The assembly device includes: The piston is lifted and placed on the support mechanism by a lifting mechanism, and at least a portion of the first thread at the lower end of the tension bolt is screwed into the first threaded hole at the upper end of the piston. A lifting mechanism is installed on the support mechanism. The lifting mechanism extends from the bottom of the piston into the piston to fix and support the lower end of the tension bolt. The lifting mechanism lifts the valve cover so that the second threaded hole at the lower end of the valve cover is fixed to the upper end of the tension bolt. The valve cover is then rotated according to the measured first length to screw at least a portion of the second thread into the second threaded hole. Wherein, the first length is the length of the first thread screwed into the first threaded hole; The supporting mechanism includes: A limiting plate, wherein a mounting hole is provided in the middle for the lower end of the piston to pass through and at least one first limiting hole is provided around the mounting hole; A bracket has a top plate, on which a through hole is provided for the lower end of the piston to pass through and at least one second limiting hole is provided around the through hole. A limiting plate is mounted on the top plate, and the mounting hole is located at the through hole, and the first limiting hole is located at the second limiting hole. A limiting pin is inserted through the first limiting hole and the second limiting hole to fix the limiting plate to the top plate; The piston is placed on the limiting plate, the lower end of the piston extends into the bracket through the mounting hole and the through hole, and the upper end of the piston is located on the limiting plate.

6. The assembly apparatus as described in claim 5, characterized in that, The bracket also has multiple support legs connected to the top plate, and the lifting mechanism includes: A connector, one end of which extends into the piston from the connecting hole at the lower end of the piston and is connected to the lower end of the tension bolt; The height adjustment component is mounted on the support leg via the support component. The height adjustment component adjusts its own height to push against the other end of the connector, thereby fixing the lower end of the tension bolt into the first threaded hole.

7. The assembly apparatus as described in claim 6, characterized in that, The height adjustment component includes: The connecting pipe has opposite third and fourth threads on the inner walls at both ends; The first column has one end inserted into one end of the connecting pipe and connected to the third thread, and the other end of the first column is connected to the support assembly; The second column has one end extending into the other end of the connecting pipe and connected to the fourth thread; A support block is installed on the other end of the second column; In this method, rotating the connecting pipe causes the support block to rise and push against the other end of the connector.

8. The assembly apparatus as described in claim 7, characterized in that, The support components include: A support plate, with the other end of the first column mounted on the support plate; Multiple inclined support members, one end of which is connected to the support plate, and the other end of which is correspondingly connected to multiple support legs.

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