JP2002357298A - Screwed joint for pressure vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screwed joint for a pressure vessel appricable for the connection part of a pressure vessel such as an outer shell of a solid rocket motor or the like by which such an inconvenience that the screw connection part is deformed and broken in the radius and axial directions is arizon depending on the degree of the inner pressure because usual joints are connected by the screwed force of the male and female screws. SOLUTION: The screw joint for a pressure vessel is constituted of a fitting section projected from at least one front end of the male part or female part and a fitting groove cut on the separation face of the pressure vessel opposite to the fitting section. In this way, the inconvenience is eliminated and the function of the pressure vessel can be retained and it is made lightweight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure vessel such as a pressure vessel for a rocket motor for burning a propellant filled therein, and a nozzle for generating a propulsion force by injecting a combustion gas in the pressure vessel. And a screw joint for a pressure vessel for integrating the two by a screw connection.

[0002]

2. Description of the Related Art Solid rocket motors (solid rocket engines) used in flying vehicles or space rockets
The nozzle is connected to the rear end of the outer shell as a cylindrical pressure vessel filled with propellant and the rear end of the outer shell, and injects combustion gas generated in the pressure vessel backward to generate propulsion. In order to connect with the front end portion, a male screw portion and a female screw portion are provided at the rear end portion of the outer shell and the front end portion of the nozzle, respectively, and these are screwed together to be integrated. If it is necessary to fly a spacecraft or space rocket for a long time using an existing solid rocket motor, cut the outer shell of the existing solid rocket motor from the middle and insert the existing The outer shell of the same diameter as the outer shell of the solid rocket motor is added to the outer shell to increase the amount of propellant charged in the outer shell and generate propulsion force for a long time to enable long flight. Have been. Even in such a case, similarly, a threaded portion and a female threaded portion are provided at both ends of the outer shell to be added to the cut portion of the outer shell of the existing solid rocket motor, and these are integrated by screwing them together. Like that.

FIG. 5 (a) shows a cylindrical outer shell rear end and a nozzle front end, or a cut portion of a solid rocket motor outer shell, and both ends of the outer shell joined together. It is sectional drawing of the screw connection part 10 conventionally provided in the joint part and comprising the external thread part 1 and the internal thread part 2 integrated. In this way, the rear end of the outer shell 3 manufactured separately, the front end of the nozzle or the cut portion of the cut outer shell 3 and both ends of the outer shell 3 inserted into the cut portion are screwed into the screw joint 10.
To facilitate the manufacture of the solid rocket motor or the filling of the propellant into the outer shell 3 or the long flight using the existing solid rocket motor. There are advantages.

However, in order to integrate the solid rocket motor, the thickness of the outer shell 3 and the like provided with the external thread portion 1 and the internal thread portion 2 is an absolute requirement from the viewpoint of flight performance in terms of weight reduction. However, even if it is possible to use only high-strength steel such as maraging steel as a material, the inside of the outer shell 3 may have a pressure of several MPa or less due to the combustion of the propellant charged therein. Since a combustion pressure load (internal pressure) 4 of several + MPa is generated, as shown in FIG. 5B, the screw connection portion 10 of the pressure vessel for a rocket motor has a radial direction between the external thread portion 1 and the internal thread portion 2. In addition to being deformed away, it may be deformed in the axial direction.

[0005] That is, a radial deformation caused by a high-pressure fluid, which is a combustion gas burned in the outer shell 3, entering (entering) the screw connection portion 10 between the external thread portion 1 and the internal thread portion 2. In addition, in the axial direction, axial deformation that occurs when the screw coupling portion 10 is pulled also occurs.

When such deformation occurs, the external thread 1
Alternatively, the internal thread portion 2 is broken, the function of the screw connection portion 10 is lost, the pressure vessel for the rocket motor cannot be maintained integrally, and the function as a solid rocket motor cannot be achieved. .

[0007] For this reason, in order to secure a necessary screw engagement height for the strength capable of resisting the internal pressure 4 generated in the outer shell 3, a screw having a high screw height is used in consideration of such deformation. This has been done in the past. However,
Increasing the number of threads increases the thickness of the outer shell 3, increases the mass of the solid rocket motor, and degrades flight performance. Or, for a space rocket, a fatal defect would occur.

For this purpose, a male thread 1 and a female thread 2
In some cases, a special screw such as the saw blade screw 6 shown in FIG. 6 is formed and screwed together. In such a case, the mass is slightly reduced to increase the coupling force. Although it can be done, it is deformed similarly to the one shown in FIG. 5 (b), so that a new drawback arises that not only requires a thread height in anticipation of this but also increases the processing cost. Will come. In FIG. 5, the threaded joint 10 is sealed in order to prevent the high-pressure fluid (combustion gas) entering the threaded joint 10 from flowing out of the fitting between the external threaded part 1 and the internal threaded part 2. O-ring.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a conventional rocket motor or other such pressure vessel having a screw joint portion which deforms.
Even if a thin plate is used, it can be reduced as much as possible, and the male thread and the female thread are less likely to be separated in the radial direction and deformed, and also less deformed in the axial direction. Another object of the present invention is to provide a pressure vessel screw joint that can prevent the screw joint from being broken and maintain the function as a pressure vessel of a rocket motor or the like.

[0010]

For this reason, the first threaded joint for a pressure vessel of the present invention is as follows.

(1) A threaded joint for a pressure vessel in which a threaded joint composed of a threaded part and a female threaded part is provided in a separating part so that pressure vessels separated into a plurality of bodies can be integrated by screwing. A fitting portion protruding in the axial direction from at least one of the front ends of the externally threaded portion or the female screw portion, and a separation surface of the pressure vessel in which the screw coupling portion front end face is fitted, facing the fitting portion. Provided
A fitting groove formed in the axial direction is provided.

(A) Thus, in the conventional threaded joint for a pressure vessel, even when a large internal pressure is applied such that the threaded joint is deformed, the radial direction and the shaft generated in the threaded joint against the internal pressure are increased. The deformation in the direction can be suppressed by the fitting of the fitting part and the fitting groove, the radial deformation that opens between the male thread part and the female thread part can be reduced, and the male thread part and the female thread part Displacement in the axial direction can be reduced.

[0013] Further, since the deformation can be reduced, the engagement of the screw between the external thread and the internal thread is maintained even when the pressure in the pressure vessel is high, with the thread having a low height,
Since the breakage of the screw connection portion is prevented and the integration of the pressure vessel can be maintained, the outflow of fluid from the inside of the pressure vessel to the outside can be prevented, and the function as the pressure vessel can be maintained. In addition, since the engagement of the screw between the male screw portion and the female screw portion can be ensured with a screw having a low height, the thickness of the pressure vessel can be reduced and the weight can be reduced.

A second threaded joint for a pressure vessel according to the present invention is the following means in addition to the above (1).

(2) The fitting section has a rectangular cross-sectional shape in the axial direction, and the shape of the fitting groove is substantially the same as the shape of the fitting section. It has been established.

(B) Thus, in addition to the above (a), by employing the means of the above (2), the engagement portion between the fitting portion and the fitting groove can be made small with a small gap. It is possible to further increase the strength with which the occurrence of deformation in the radial direction and the axial direction generated in the joint portion can be suppressed.

A third threaded joint for a pressure vessel according to the present invention is the following means in addition to the above (1).

(3) The front end cross-sectional shape of the fitting portion is provided to be inclined toward the center of the thickness of the pressure vessel which is separated from the inner peripheral surface or the outer peripheral surface of the pressure vessel from the screw connection portion. The cross-sectional shape is tapered in the direction,
The shape of the fitting groove was substantially the same as that of the fitting portion, and was cut from the inner peripheral surface or the outer peripheral surface side of the separation portion of the pressure vessel toward the center of the thickness of the pressure vessel.

(C) Thus, in addition to the above (a), by employing the means of the above (3), the processing of the fitting portion and the fitting groove provided in the separation portion of the pressure vessel can be performed by: It can be made easily from the outer peripheral surface side, and especially, the processing of the fitting groove provided at the joint of the pressure vessel can be done in a short time,
The manufacturing cost of the pressure vessel can be reduced.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a threaded joint for a pressure vessel according to the present invention will be described below with reference to the drawings. In the drawings, the same or similar members as those shown in FIGS. 5 and 6 are denoted by the same reference numerals, and description thereof will be omitted. FIG. 1 is a partial cross-sectional view of a threaded joint showing a first embodiment of the threaded joint for a pressure vessel of the present invention.

As shown in the figure, the joint portion of the outer shell 3 forming the pressure vessel for a rocket motor as a pressure vessel has the same structure as the male thread portion 1 and the female thread portion 2 shown in FIGS. A threaded connection portion 10 provided with a
By screwing screws provided on the outer periphery and the inner periphery of the internal thread portion 2, the separated outer shell 3 is integrated. In addition, the male screw part 1 and the female screw part 2
A rectangular fitting portion 71 protruding from the front end is provided, and the separation surface 9 of the outer shell 3 in which the front ends of the male screw portion 1 and the female screw portion 2 are fitted respectively faces the fitting portion 71. A rectangular fitting groove 81 having substantially the same shape as the cross-sectional shape of the fitting portion 71 is formed in the screw coupling portion 1.
It is drilled in the axial direction away from zero.

In the threaded joint for a pressure vessel according to the present embodiment, as described above, the fitting portions 71 are provided at the front ends of the male thread portion 1 and the female thread portion 2, respectively, and the male thread portion 1 and the female thread portion 2 are provided.
At the same time, the fitting portion 71 enters the fitting groove 81 provided on the separation surface 9 of the outer shell 3, and the fitting portion 71 and the fitting groove 81 are fitted.

As a result, in the conventional threaded joint for a pressure vessel shown in FIGS. 5 (a) and 6 (b), as shown in FIG. Also, when a large internal pressure such as a combustion load pressure is applied to the outer shell 3 that deforms in the axial direction, that is, the so-called screw coupling portion 10 is deformed, the connection between the fitting portion 71 and the fitting groove 81 causes The deformation of the external thread portion 1 and the internal thread portion 2 is suppressed from each other, whereby it is possible to counter internal pressure, and it is possible to suppress the occurrence of the deformation that has conventionally occurred in the screw coupling portion 10.

That is, the fitting portion 71 which has entered the fitting groove 81 suppresses the deformation of the screw coupling portion 10, so that the space between the male screw portion 1 and the female screw portion 2 can be prevented from opening, and at the same time, the male screw portion 1 It is possible to have a strength capable of preventing the axial deviation from the screw portion 2.

Further, even when the internal pressure 4 becomes large, the screw engagement between the male screw portion 1 and the female screw portion 2 can be ensured by the screw having a low screw height, so that the screw coupling portion 10 is prevented from being broken. Further, since the integration of the outer shell 3 is maintained, the outflow of the combustion gas from the inside of the outer shell 3 to the outside can be prevented. Rocket motor function can be maintained. Furthermore, a male thread part 1 and a female thread part 2
Can be secured by a screw having a low screw height, the thickness of the outer shell 3 can be reduced, and the weight of the rocket motor can be reduced.

Next, FIG. 2 is a partial cross-sectional view of a threaded joint showing a second embodiment of the threaded joint for a pressure vessel of the present invention. In the threaded joint for a pressure vessel according to the present embodiment, the front ends of the external thread portion 1 and the internal thread portion 2 are formed in the outer shell 3, and the outer shell 3 is separated from the outer peripheral surface by a screw thickness portion 10 at the center of the plate thickness. And a wedge-shaped fitting portion 72 is provided on the separation surface 10 of the outer shell 3.
The fitting groove 82 having substantially the same shape as that of No. 2 is formed to be inclined from the separation surface 9 toward the center of the plate thickness. That is, the fitting grooves 82 of this embodiment form the separation surfaces 9 of the divided outer shells 3 respectively.

The threaded joint for a pressure vessel according to this embodiment can provide the same operation and effects as those of the threaded joint for a pressure vessel according to the first embodiment described above, and the threaded joint for a pressure vessel according to this embodiment. In the above, the fitting groove 82 is formed in a tapered shape formed from the inner peripheral surface or the outer peripheral surface of the outer shell 3 to the center of the plate thickness separated from the screw coupling portion 10, so that the processing of the fitting groove 82 is performed. In addition, there is an advantage that processing can be performed easily and in a short time as compared with the processing of the fitting groove 81 of the first embodiment.

Next, FIG. 3 is a partial cross-sectional view of a threaded joint showing a third embodiment of the threaded joint for a pressure vessel of the present invention.

In the present embodiment, a fitting portion 71 provided at the front end of each of the male screw portion 1 and the female screw portion 2 in the first embodiment is provided at the front end portion of the male screw portion 1. A fitting groove 81 similar to that provided in the first embodiment is provided only on the separation surface 9 of the outer shell 3 into which the front end of the male screw portion 1 is fitted.

By doing so, the fitting portion 7
1 and the processing of the fitting groove 81 can be halved as compared with the first embodiment, and the fitting portion 81 is provided at the front end of the external thread portion 1 provided on the inner peripheral side of the outer shell 3. As a result, the deformation of the male screw portion 1 can be suppressed, the strength comparable to that of the first embodiment can be obtained, and the deformation of the screw connection portion can be prevented.

Next, FIG. 4 is a partial cross-sectional view of a threaded joint 10 showing a fourth embodiment of the threaded joint for a pressure vessel of the present invention. In the present embodiment, a fitting portion 72, which is provided at the front end of each of the male screw portion 1 and the female screw portion 2 in the second embodiment, is provided at the front end portion of the male screw portion 1, and A fitting groove 8 similar to that provided in the second embodiment only on the end face of the outer shell 3 into which the front end of the portion 1 is fitted.
2 was provided.

By doing so, the fitting portion 7
2 and the processing of the fitting groove 82 can be halved as compared with the second embodiment, and the fitting portion 82 is provided at the front end of the external thread portion 1 provided on the inner peripheral side of the outer shell 3.
Is provided, the deformation of the male screw portion 1 can be suppressed, the strength comparable to that of the second embodiment can be obtained, and the deformation of the screw connection portion can be prevented.

Although the embodiment of the threaded joint for a pressure vessel according to the present invention has been described above, the present invention is not limited to the above-described embodiment. 2, the screw thread and the screw groove can be formed into a saw-tooth screw 6 in the same manner as that shown in FIG. 6, so that the processing cost is increased, but the thickness of the outer shell 3 is increased. Can be made thinner, and it is possible to further reduce the weight.

[0034]

As described above, the threaded joint for a pressure vessel of the present invention is provided at a threaded joint in a threaded joint for a pressure vessel in which a plurality of pressure vessels are integrated by screwing. A fitting portion protruding from at least one of the front ends of the male screw portion and the female screw portion, and a fitting groove formed in the separation surface where the front end of the screw coupling portion is fitted are formed so as to face the fitting portion.

Thus, even when a large internal pressure is applied, it is possible to suppress the occurrence of radial and axial deformation at the threaded joint, so that the male thread and the female thread are not separated from each other.
It can be made strong enough to prevent the axial displacement between the external thread and the internal thread, and the thread of the low thread can secure the engagement of the threaded joint, prevent breakage, and maintain the integration of the pressure vessel As a result, outflow of fluid from the inside is prevented, and the function of the pressure vessel can be maintained. Further, since the screw engagement between the male screw portion and the female screw portion can be secured with a low screw, the thickness of the pressure vessel can be reduced and the weight can be reduced.

In the threaded joint for a pressure vessel according to the present invention, the fitting portion has a rectangular cross section and the fitting groove has substantially the same shape as the fitting portion.

As a result, the engagement between the fitting portion and the fitting groove can be reduced with a small gap, and the strength for suppressing radial and axial deformation occurring in the screw connection portion against internal pressure can be increased.

Further, in the threaded joint for a pressure vessel according to the present invention, the front end cross-sectional shape of the fitting portion is axially directed toward the center of the thickness of the pressure vessel away from the screw connection from the inner or outer periphery of the pressure vessel. The fitting groove has a sectional shape substantially the same as that of the fitting portion.

With this arrangement, the fitting portion and the fitting groove provided in the separation portion of the pressure vessel can be easily processed from the inner and outer circumferences of the separation portion of the pressure container. In addition, the processing of the fitting groove can be performed in a short time, and the manufacturing cost of the pressure vessel can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a threaded joint showing a first embodiment of a threaded joint for a pressure vessel of the present invention;

FIG. 2 is a partial cross-sectional view of a threaded joint showing a second embodiment of the threaded joint for a pressure vessel of the present invention;

FIG. 3 is a partial cross-sectional view of a threaded joint showing a third embodiment of the threaded joint for a pressure vessel of the present invention;

FIG. 4 is a partial cross-sectional view of a threaded joint showing a fourth embodiment of the threaded joint for a pressure vessel of the present invention;

5A and 5B are partial cross-sectional views of a threaded joint showing an example of a conventional threaded joint for a pressure vessel. FIG. 5A shows a normal coupling state, and FIG. 5B shows a large pressure vessel internal pressure. The figure showing the screw coupling part deformation state when it becomes

FIG. 6 is a partial cross-sectional view of a threaded joint showing another example of a conventional threaded joint for a pressure vessel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Male thread part 2 Female thread part 3 Outer shell 4 Internal pressure 5 O-ring 6 Serrated screw 71, 72 Fitting part 81, 82 Fitting groove 9 Separation surface 10 Screw connection part

 ──────────────────────────────────────────────────続 き The continuation of the front page F term (reference) 3E072 DB10 3H013 JC02

Claims (3)

[Claims] 1. A threaded joint for a pressure vessel, wherein a threaded portion comprising a threaded portion and a female threaded portion is provided in a separating portion, and the pressure vessel separated into a plurality of bodies is integrated by screwing. A fitting portion protruding from at least one front end of the female screw portion, and a fitting groove formed in the separation surface of the pressure vessel in which the front end face of the screw coupling portion fits is formed so as to face the fitting portion. A threaded joint for a pressure vessel, characterized in that: 2. The fitting portion has a rectangular cross-sectional shape in the axial direction, and the fitting groove has substantially the same shape as the shape of the fitting portion, and is formed in the separation surface in an axial direction. The threaded joint for a pressure vessel according to claim 1, wherein 3. The fitting portion has a front end cross-sectional shape that is inclined in an axial direction from an inner circumference or an outer circumference of the pressure vessel to a center portion of the pressure vessel plate thickness that is separated from the screw connection portion. 2. The threaded joint for a pressure vessel according to claim 1, wherein a groove is formed on the separation surface in substantially the same shape as the shape of the fitting portion.