JPS61274919A - Method for laminating insulator preform to inner surface of case - Google Patents

Abstract

PURPOSE:To enable the entire surface adhesion of an insulator and the inner surface of a case by preventing the generation of an air layer between both of them, by hermetically closing the interior of the case and pressing a preform to the inner surface of the case in an evacuated state. CONSTITUTION:An insert pipe 5 covered with a preform 3 in a folded state is inserted in a motor case 1 and a rear closure 31 is engaged with the rear end part of the pipe 5 to close the front and rear ends of the motor case 1 along with a forward closure 21 and the forward and rear closures 21, 31 are mutually tightned by using a connection rod 33 and nuts 34, 34. Subsequently, a lock valve 24 is connected to a vacuum source 28 along with a change-over valve 27 and an expandable body 10 and the motor case 1 are evacuated. Especially, the motor case 1 is evacuated so as to reach a high vacuum degree through a cock valve 24. Thereafter, the change-over valve 27 is gradually changed over to an atmospheric side while evacuation is succeeded through the cock valve 24 to introduce atmospheric pressure and the preform is contacted with the inner surface of the motor case 1 under high vacuum through an adhesive while forcibly expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of attaching an insulator preform to the inner surface of a motor case of a rocket motor, for example, and more specifically, a method of attaching an insulator preform to the inner surface of a motor case of a rocket motor. This relates to a method of inserting the insulator preform into the inner surface of the case and then inflating the inflatable bag to press and adhere the insulator preform to the inner surface of the case.

(Prior art) 1 [An insulator attached to the inner surface of a motor case of a rocket motor protects the case from high-temperature combustion gas of rocket propellant, or if the case is made of fiber-reinforced resin (FRP) etc. When it is made of a material with a high temperature, it also serves to prevent the permeation of the combustion gases. Such an insulator is usually preformed from heat-resistant rubber or the like into a cylindrical body (insulator preform) that fits the inner surface of the case, and is affixed to the inner surface of the case by pressure bonding.

FIG. 4 shows an example of a conventional device for attaching the insulator preform (hereinafter referred to as preform) to the motor case of a rocket motor. In the same figure,
1 is a motor case, 2 is a workbench on which this motor case is placed, 3 is a preform, and this preform 3 is designated by the symbol 3.
It is attached to the required area of the inner surface of the motor case 1 as shown by I.

Reference numeral 5 denotes an insert pipe, which has a length that can pass through the motor case 1, is closed at its rear end (the right end in the drawing), and has a plurality of through holes 6 in its middle portion.

T is a cock valve attached to the front end of the insert pipe 5 and is connected to a pressure air source 8 via a flexible hose.

10 is an inflatable bag made of a flexible and elastic material such as nylon, and when inflated, an insulator 3
It is formed into a long bag shape that can press the entire part where the
A member 11 is fitted into the insert pipe 5 and seals both ends.
．． 111 to the pipe 5.

The above device is used as follows.

(1) Outside the motor case 1, insert the insert pipe 5
The preform 3 is fitted into the expandable bag 10 which is fitted into the inflatable bag 10.

(2) Connect the cock valve 7 to the pressurized air source 8 to inflate the inflatable bag 10 halfway, and hold the fitted preform 3 by the outer periphery of the inflatable bag.

(3) Apply adhesive to the inner surface of the motor case 1.

(41) The structure obtained in step 21 is inserted into the motor case 1 as shown in the drawing, and the insert pipe 5 is supported using an appropriate support means.

(5) Pressurized air is further supplied through the cock valve 7 to sufficiently inflate the expandable body 10. As a result, the preform 3 is pressed against the inner surface of the motor case 1 via the adhesive.

(6) Curing the adhesive.

Incidentally, a solid propellant is loaded into the motor case 1 to which the insulator 3' is attached as described above, and the propellant and the insulator 3' are usually joined integrally.

(Problem) However, when using the above-mentioned conventional adhesion method, in the process of pressing the preform against the inner surface of the case, some air cannot escape and an air layer is formed here, resulting in the formation of an air layer in the core part. There was a drawback that poor adhesion was caused.

Incidentally, in a rocket motor, as mentioned above, the propellant is usually integrated with the insulator 3' and held in the motor case 1 via the adhesive layer, so if the air layer is present, the core will not be held. Power decreases. On the other hand, due to the difference in their coefficients of thermal expansion, the propellant and the motor case tend to behave differently when, for example, the environmental temperature changes, but are restrained and retained their shape by the holding force. Therefore, if a portion with poor holding power such as an air layer is present, the above-mentioned restraining force will be concentrated around the core, causing separation and expanding the air layer range. As this phenomenon progresses, the stress distribution inside the propellant becomes uneven and a crank may occur, which is extremely dangerous as it increases the combustion area. Alternatively, where the insulator is exposed to high-temperature combustion gas, the part of the insulator with an intervening gas layer burns out, causing so-called case erosion in the motor case.

This is a fatal flaw for the motor case as a high-pressure container.

For this reason, after the insulator is attached, the presence or absence of an air layer is checked using an ultrasonic flaw detector, and if a harmful air layer is detected, it is repaired, but this work requires a lot of effort. It takes a lot of time and man-hours.

Therefore, the problem of the present invention is to prevent the generation of the gas layer as described above.

(Means of the present invention) The means of the present invention that solves the above problems includes the step (4) of fitting a preform into an inflatable bag and inserting it into a motor case.
) and the step (5) of inflating the inflatable bag and pressing the preform against the inner surface of the case, a step of sealing the case, and a step of venting the inside of the sealed case. It has been established.

According to the above means, since the preform is pressed against the inner surface of the case under vacuum, no air layer is formed.

(Embodiment) FIGS. 1, 2, and 3 are explanatory diagrams of an apparatus according to an embodiment of the present invention, in which 1 is the motor case of the rocket motor, and 2 is the workbench.

21 and 31 are a forward closure and a rear closure for respectively closing the front end (left end in FIG. 1) and rear end (right end in FIG. 1) of the motor case 1;
Seal rings 2 are attached to the forward and rear closures, respectively, and can be in airtight contact with the front and rear end surfaces of the motor case 1, respectively. This allows the peripheral surfaces of both ends to be tightened. 33 is, for example, three connecting rods, whose both ends are inserted into the forward and rear closures, and the nuts 34, 34k are tightened to connect the two a-jars 21, 31tl-. In this state, reference numerals 25 and 35 are through holes opened in the forward and rear ajars, respectively, at the axial center position of the motor case 1, and the insert pipe 5 can be inserted into these through holes. 26 and 36 are O-rings for ensuring airtightness between the insert pipe and the through holes 25 and 35, 23 is a through hole opened in the forward closure 21 and opened into the motor case 1, and 24 is the opening of the closure 21. This is a cock valve that is attached to the case 1 and opened into the case 1. Both closures 21, 31 and their electrically conductive parts have been removed from the initial motor case 1.

The expandable device 0 is attached to the insert pipe 5 through the seal member 11t as in the conventional case, and the fitting operation of the preform 3 is carried out in the same manner as in the conventional step (1). and perform the insertion step according to steps (21, (3) and (4)).

Incidentally, the procedure described below is a further improvement of the above process. That is, (a), insert pipe 5 with forward closure 2
1 and attach the switching valve 2T to the front end of the pipe 5.

(b) Connect the switching valve 2γ to the vacuum source 28 to suck the air inside the insert pipe 5.

As a result, the inside of the town expansion bag 10 is vented through the through hole 6, so that the town expansion bag deflates and reduces its diameter.

e→, the preform 3 is placed in this diameter-reduced town expansion bag 10.
and fold it in the longitudinal direction as shown in FIGS. 2 and 3.

2) Using a relatively weak forceps 41, hold the folded preform 3 with appropriate pinches to maintain its shape.

(E) 1. A strong drawstring 42 is tied to the tied yarn 41 in sequence and placed on the side of the preform 3, and its front portion is pulled through the through hole 23 and pulled out. A resilient bonding 29 is applied to this lead-through portion to seal it.

(f) Apply adhesive to the inner surface of the motor case 1.

(g) Insert the insert pipe 5 with the preform 3 folded and attached into the motor case 1.

According to the above procedure (a) to g), preform 3
Since the insert pipe 5 is gathered into a shape and retained in a shape, it is possible to prevent contact with the inner surface of the motor case during insertion.Therefore, no damage is caused to the adhesive coating layer on the inner surface.

After completing the insertion work according to the above steps (a) to g), carry out the steps described below.

In the sealing process (A-1') of the motor case 1, the rear closure 31 is fitted to the rear end of the insert pipe 5, and the front and rear ends of the motor case 1 are closed together with the forward claw and the jaw 21. .

At this time, if the motor case 1 is breathable as described above, cover the motor case with a non-breathable tube 43 made of nylon film or the like, and seal both ends of the tube with the L-shaped cross section. 22 and 32 to keep the core airtight.

(A-2) Tighten the forward and rear closures 21.31 together using the connecting rod 33 and nuts 34,34.

(2) Venting step (B-1): The cock valve 24 and the switching valve 2γ are connected to the vacuum source 28, and the inside of the expandable body 10 and the inside of the motor case 1 are depressurized through both valves. In particular, air is evacuated through the cock valve 24 until the inside of the motor case becomes a high vacuum.

(0, Pressing step (C-1), while continuing to vent air using the cock valve 24, the switching valve 2T is gradually switched to the atmosphere side.

As a result, atmospheric pressure is introduced into the inflatable bag 10 via the insert pipe 5, and the inflatable bag expands while pushing the preform 3 outward. In this process, the yarn 41 that was hugging the preform is cut.

(C-2>, the yarn 41 cut above by pulling the drawstring 42
is pulled out of the forward closure 21.

(C-3) Atmospheric pressure is further introduced through the switching valve 27.

As a result, the preform 3 is expanded further and passes through the state shown in FIG. 4 and is pressed against the inner surface of the motor case via the adhesive under high vacuum.

(Effects) As explained above, since the present invention presses the preform in a state in which air is removed from the inside of the case, there is no intervening air layer between the insulator formed by the present invention and the inner surface of the case. Both can be fully bonded.

Furthermore, in the embodiment, damage to the adhesive coating layer can be prevented as described above by inserting the preform with the preform in a concave position, so that partial adhesion failure due to this damage can also be avoided.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is an explanatory diagram of an apparatus according to an embodiment of the present invention;
The figure is an enlarged sectional view of the main part of Figure 1, and Figure 3 is I-1 in Figure 2.
The cross-sectional view in FIG. 4 is an explanatory diagram of an apparatus related to a conventional method. 1... Case (motor case of rocket motor) 3.
... Insulator preform 3I ... Pasted insulator 5 ... Insert pipe 10 for insertion ... Expandable bag 21 ... Forward closure 24 for sealing ... Cock valve for venting

Claims (1)

[Claims] In the method of fitting an insulator preform into an inflatable bag and inserting it into a case, and then inflating the inflatable bag, the insulator preform is pressed against and attached to the inner surface of the case, the step of inserting it into the case. and the above,
A method of adhering an insulator preform to the inner surface of a case, which includes a step of sealing the case and a step of venting the inside of the sealed case between the step of inflating the inflatable bag.