Cold mounting method of check valve

Abstract

A cold mounting method for a check valve relates to the technical field of check valves, and comprises the following steps: firstly, pressing a ball seat into an inner cavity of a sleeve so as to pre-compress a spring; under the condition that the spring is kept in a compressed state, the sleeve is subjected to low-temperature treatment; and finally, a steel ball is placed in the cup-shaped part, and the sleeve subjected to low-temperature treatment is inserted into an assembly cavity of the cup-shaped part. According to the method, low-temperature treatment is used for replacing traditional heat treatment, and high-temperature deformation of the part can be effectively avoided. In addition, through pre-compression of the spring, the rigidity of the spring is increased, and deformation of the spring in the assembling process is avoided. According to the cold assembly method, the assembly qualification rate can be effectively increased, the assembly time is shortened, and the consumption of auxiliary materials is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of check valves, in particular to a cold assembly method of a check valve. BACKGROUND

[0002] Check valves are used to block the backflow of medium and are widely used in industry. A commonly used micro check valve in a nozzle is one that exerts pressure on a steel ball under the action of a spring to block the medium through the close fit between the steel ball and a cup-shaped member. When the medium flows in the same direction, the steel ball can be pushed away to overcome the spring force, thereby maintaining the flow of the medium. When the medium flows in the opposite direction, the pressure of the medium is consistent with the spring force, and the steel ball is tightly pressed in the cup-shaped member, maintaining the medium blocking state.

[0003] The most common failure cause of this check valve is that the seal is unqualified due to the poor fit between the steel ball and the taper surface of the cup-shaped member, or the opening pressure of the check valve is unqualified due to the performance degradation of the spring. Therefore, the check valve in repair state often needs to replace the cup-shaped member, the steel ball or the spring without damaging the remaining parts. Moreover, the structure of this type of check valve is small, the spring and the steel ball are in a movable state, and the cup-shaped member and the sleeve are in an interference fit, which causes the spring to be easily deflected during assembly, resulting in unqualified assembly.

[0004] The existing assembly method for this type of check valve is to heat the cup-shaped member to make it expand, then insert the sleeve into the expanded cup-shaped member, and realize the interference fit after the cup-shaped member cools down. This method has the potential risk of part thermal deformation on the one hand, and lacks effective positioning of the spring and the steel ball on the other hand, which can easily cause secondary failure due to spring deflection. SUMMARY

[0005] The purpose of the present application is to provide a cold assembly method of a check valve, which is simple and convenient to operate, can quickly and efficiently assemble the micro check valve, and effectively avoids part thermal deformation while achieving precise positioning.

[0006] The embodiments of the present application are implemented as follows: A cold assembly method of a check valve, comprising: S1. Low-temperature treatment is performed on the stopper, and the stopper is pressed into the sleeve; S2. The spring and the ball seat are sequentially loaded, and the ball seat is pressed into the inner cavity of the sleeve, thereby pre-compressing the spring; S3. The sleeve is subjected to low-temperature treatment while the spring is kept in a compressed state; S4. The steel ball is placed in the cup-shaped member, and the low-temperature treated sleeve is inserted into the assembly cavity of the cup-shaped member.

[0007] Further, in other preferable embodiments of the present application, in the step S1, the low-temperature treatment of the stop block is placing it in liquid nitrogen for 3-5 min.

[0008] Further, in other preferable embodiments of the present application, in the step S1, the assembly idle period after the low-temperature treatment of the stop block is ≤90 s.

[0009] Further, in other preferable embodiments of the present application, in the step S2, the compression amount of the spring is 30% of its free length.

[0010] Further, in other preferable embodiments of the present application, in the step S2, the pre-compression pressure of the spring is 5-8 N, and the axis deviation is ≤0.05 mm.

[0011] Further, in other preferable embodiments of the present application, in the step S3, the low-temperature treatment of the sleeve is freezing it at -30--20℃ for 1-3 h, and then placing it in liquid nitrogen for 3-5 min.

[0012] Further, in other preferable embodiments of the present application, in the step S3, the assembly idle period after the low-temperature treatment of the sleeve is ≤90 s.

[0013] Further, in other preferable embodiments of the present application, in the step S3, the shrinkage amount of the sleeve is 0.02-0.05 mm, the gap between the sleeve and the cavity wall of the assembly cavity after the shrinkage of the sleeve is 0.001-0.003 mm, and the assembly coaxiality is ≤0.03 mm.

[0014] Further, in other preferable embodiments of the present application, in the step S4, after the assembly is completed, the check valve is placed at room temperature for natural temperature rise.

[0015] The beneficial effects of the embodiments of the present application are: The embodiments of the present application provide a cold assembly method of a check valve, which first compresses a ball seat into the inner cavity of a sleeve to pre-compress a spring, then performs low-temperature treatment on the sleeve while keeping the spring in the compressed state, and finally puts a steel ball into a cup-shaped piece and inserts the low-temperature treated sleeve into the assembly cavity of the cup-shaped piece. By this method, the low-temperature treatment is used to replace the traditional heat treatment, which can effectively avoid the high-temperature deformation of the parts. In addition, the pre-compression of the spring increases the rigidity of the spring and avoids its deformation during the assembly process. The cold assembly method can effectively improve the assembly qualification rate, shorten the assembly time, and reduce the auxiliary material consumption. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0017] Fig. 1 A sectional view of a check valve provided by the embodiments of the present application; Fig. 2 A sectional view of a check valve provided by the embodiments of the present application at A-A; Fig. 3 A sectional view of a check valve provided by the embodiments of the present application at B-B.

[0018] Figure legend: 100-check valve; 110-cup-shaped member; 111-fitting cavity; 112-liquid inlet passage; 120-sleeve; 121-internal cavity; 130-stop block; 131-second flow passage; 140-ball seat; 141-first flow passage; 150-spring; 160-steel ball. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0020] EMBODIMENT

[0021] The present embodiment provides a cold mounting method of a check valve 100, and the structure of the check valve 100 is as shown in Figs. 1-3 .

[0022] The check valve 100 comprises a cup-shaped part 110 and a sleeve 120, the cup-shaped part 110 is inwardly recessed at one end thereof along the axial direction to form an assembly cavity 111, one end of the sleeve 120 is inserted into the assembly cavity 111, and the outer wall of the sleeve 120 is in interference fit with the cavity wall of the assembly cavity 111; the sleeve 120 is provided with an inner cavity 121 penetrating along the axial direction thereof, the inner cavity 121 is internally provided with a stop block 130 and a ball seat 140, the stop block 130 is in interference fit with the cavity wall of the inner cavity 121, the ball seat 140 is located between the stop block 130 and the cavity bottom of the assembly cavity 111, and is in sliding fit with the inner cavity 121, and the stop block 130 and the ball seat 140 are provided with a spring 150; the ball seat 140 and the cavity bottom of the assembly cavity 111 are provided with a steel ball, the cavity bottom of the assembly cavity 111 is provided with a liquid inlet channel 112 penetrating therethrough, and one end of the liquid inlet channel 112 towards the steel ball is provided with a tapered guide surface for cooperating with the steel ball; the side wall of the ball seat 140 is provided with a first flow passage 141 penetrating along the axial direction thereof, and the side wall of the stop block 130 is provided with a second flow passage 131 penetrating along the axial direction thereof.

[0023] In the case of forward flow, the medium enters from the liquid inlet channel 112, pushes away the ball seat 140 to overcome the elastic force of the spring 150, and the medium sequentially passes through the first flow passage 141 and the second flow passage 131 to maintain the flow of the medium. In the case of reverse flow, the direction of the medium flow is consistent with the direction of the elastic force of the spring 150, and the steel ball is pressed into the tapered guide surface to maintain the cutting off of the medium.

[0024] In the prior art, the assembly of the check valve 100 is to first heat the sleeve 120 to expand it, then install the stop block 130 in place, and after cooling, complete the interference fit of the sleeve 120 and the stop block 130; then heat the cup-shaped part 110 to make it expand, sequentially put the steel ball 160, the ball seat 140 and the spring 150 into the assembly cavity 111, align the sleeve 120, press the sleeve 120 into the assembly cavity 111, and after cooling, complete the interference fit of the sleeve 120 and the cup-shaped part 110. During the compression process, since the steel ball 160 and the ball seat 140 are not fixed, they are prone to displacement during the compression process, causing the force direction of the spring 150 to be inclined relative to the axial direction. In this assembly method, the spring 150 is in a natural length state, has insufficient rigidity, and is not enough to resist the inclined force, thereby causing the spring 150 to deform. During the entire assembly process, the spring 150 is hidden inside the part and is in an invisible state, and the operator cannot make timely adjustments according to the force condition of the spring 150, ultimately resulting in a low assembly qualification rate of the product.

[0025] Based on the above reasons, the present embodiment provides a brand new cold assembly method, which comprises: S1. low-temperature treatment is performed on the stop block 130, and the stop block 130 is pressed into the sleeve 120; S2. Load the spring 150 and the ball seat 140 in sequence, press the ball seat 140 into the inner cavity 121 of the sleeve 120, thereby pre-compress the spring 150; S3. Perform low-temperature treatment on the sleeve 120 while keeping the spring 150 in the compressed state; S4. Put the steel ball into the cup-shaped piece 110, and insert the low-temperature treated sleeve 120 into the assembly cavity 111 of the cup-shaped piece 110.

[0026] In the S1 step, the stopper 130 is subjected to low-temperature treatment by being placed in liquid nitrogen for 3-5 min. After the low-temperature treatment, the size of the stopper 130 shrinks as a whole, so that it can smoothly enter the inner cavity 121 of the sleeve 120 to reach the installation position. After the temperature rises, the stopper 130 restores its original size, thereby completing the interference fit with the sleeve 120. Further, in the S1 step, the assembly window period of the stopper 130 after the low-temperature treatment is ≤90 s.

[0027] In addition, in the S2 step, the compression amount of the spring 150 is 30% of its free length. Under this compression amount, it can be ensured that the spring 150 has sufficient rigidity to avoid deformation in subsequent assembly.

[0028] Further, in the S2 step, the pre-compression pressure of the spring 150 is 5-8 N, and the axial deviation is ≤0.05 mm. During the entire pre-compression process, the compression process of the spring 150 is in a visible state, and by uniformly pressing the spring 150, the axial deviation can be more effectively controlled.

[0029] In the S3 step, the low-temperature treatment of the sleeve 120 is first frozen at -30 to -20℃ for 1-3 h, and then cooled in liquid nitrogen for 3-5 min. Freezing at -30 to -20℃ can preliminarily shrink the sleeve 120, thereby increasing the friction between the sleeve 120 and the ball seat 140, and temporarily fixing the ball seat 140. In the subsequent assembly process, the ball seat 140 will not be ejected by the spring 150, and the compression state of the spring 150 will be maintained. It should be particularly noted that although the ball seat 140 will also shrink to a certain extent in the frozen state, the sleeve 120 on the outside shrinks more than the ball seat 140 on the inside, so the ball seat 140 can be fixed. After the pre-fixing of the ball seat 140 in the frozen state, the sleeve 120 is quickly shrunk in liquid nitrogen before the final assembly, so as to meet the assembly requirements while avoiding excessive shrinkage causing extrusion deformation between the inner wall of the sleeve 120 and the ball seat 140 and the stopper 130. Similarly, in the S3 step, the assembly window period of the sleeve 120 after the low-temperature treatment is ≤90 s.

[0030] Further, in the S3 step, the sleeve 120 is contracted by 0.02-0.05 mm, and the gap between the sleeve 120 and the cavity wall of the assembly cavity 111 is 0.001-0.003 mm after the contraction of the sleeve 120, and the assembly coaxiality is ≤0.03 mm. In this condition, better assembly precision can be ensured.

[0031] In the S4 step, after the assembly is completed, the check valve 100 is placed at room temperature for natural temperature rise. With the temperature rise, the sleeve 120 returns to the original size, thereby completing the interference fit with the cup-shaped part 110.

[0032] In summary, the cold assembly method of the check valve 100 provided by the embodiment of the present application first presses the ball seat 140 into the inner cavity 121 of the sleeve 120, thereby pre-compressing the spring 150; and under the condition that the spring 150 is kept in the compressed state, the sleeve 120 is subjected to low-temperature treatment; finally, the steel ball is placed in the cup-shaped part 110, and the sleeve 120 subjected to the low-temperature treatment is inserted into the assembly cavity 111 of the cup-shaped part 110. By this method, the low-temperature treatment is used to replace the traditional heat treatment, and the high-temperature deformation of the parts can be effectively avoided. In addition, by pre-compressing the spring 150, the rigidity of the spring 150 is increased, and the deformation of the spring 150 in the assembly process is avoided. The cold assembly method can effectively improve the assembly qualification rate, shorten the assembly working hours, and reduce the auxiliary material consumption.

[0033] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A cold mounting method for a check valve, characterized by, The application relates to a method for assembling a check valve, comprising the following steps: S1. low-temperature treatment of a stop block and pressing the stop block into a sleeve; S2. sequentially loading a spring and a ball seat, pressing the ball seat into the inner cavity of the sleeve, thereby pre-compressing the spring; S3. low-temperature treatment of the sleeve while keeping the spring in a compressed state; S4. placing a steel ball in a cup-shaped piece and inserting the low-temperature treated sleeve into the assembly cavity of the cup-shaped piece.

2. The cold-fitting method according to claim 1, characterized by In the S1 step, the low-temperature treatment of the stop block is carried out by placing the stop block in liquid nitrogen for 3-5 min.

3. The cold-fitting method according to claim 2, wherein In the S1 step, the assembly empty window period of the stop block after the low-temperature treatment is less than or equal to 90 s.

4. The cold-fitting method according to claim 1, wherein In the S2 step, the compression amount of the spring is 30% of the free length of the spring.

5. The cold fitting method of claim 4, wherein In the S2 step, the pre-compression pressure of the spring is 5-8 N, and the axial deviation is less than or equal to 0.05 mm.

6. The cold charging method of claim 1, wherein In the S3 step, the low-temperature treatment of the sleeve is carried out by first freezing the sleeve at-30 to-20 DEG C for 1-3 h, and then placing the sleeve in liquid nitrogen for 3-5 min.

7. The cold fitting method of claim 6, wherein In the S3 step, the assembly empty window period of the sleeve after the low-temperature treatment is less than or equal to 90 s.

8. The cold fitting method of claim 7, wherein In the S3 step, the shrinkage amount of the sleeve is 0.02-0.05 mm, the gap between the sleeve and the cavity wall of the assembly cavity after the shrinkage of the sleeve is 0.001-0.003 mm, and the assembly coaxiality is less than or equal to 0.03 mm.

9. The cold fitting method of claim 8, wherein, In the S4 step, after the assembly is completed, the check valve is placed at room temperature for natural temperature rise.

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