Method for manufacturing a solid rocket motor, surface treatment apparatus, and surface treatment system

Abstract

The present invention provides a method for manufacturing a solid rocket motor, a surface treatment apparatus, and a surface treatment system that can stably treat the surface of an insulating material. [Solution] A method for manufacturing a solid rocket motor, comprising a surface treatment step of irradiating the surface of insulation 14 provided on the inner surface of the combustion vessel 10 of the solid rocket motor with atmospheric pressure plasma. Also comprising a surface treatment apparatus 100 and a surface treatment system 150 equipped with the surface treatment apparatus 100, comprising a plasma irradiation unit 102 having a nozzle 104 for irradiating plasma and an arm portion 106 that drives the tip of the nozzle 104 toward the insulation 14, an irradiation unit suspension unit 110 having an irradiation unit moving means 108 for moving the plasma irradiation unit 102, and an irradiation control unit 112 that controls the distance between the tip of the nozzle 104 and the surface of the insulation 14 using the arm portion 106 and the irradiation unit moving means 108.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a solid rocket motor, a surface treatment apparatus, and a surface treatment system.

Background Art

[0002] As a solid rocket motor, for example, the following Patent Document 1 has been proposed. In the solid rocket motor, a heat insulating material (insulation) is provided inside a casing, and a solid propellant is provided on the inner side of the heat insulating material. Providing the heat insulating material suppresses the transfer of heat generated in the internal space to the casing.

[0003] The installation of the solid propellant into the casing is performed by adhering the solid propellant to the heat insulating material provided inside the casing. Further, as pretreatments for adhering the solid propellant to the heat insulating material, a method of cleaning the surface of the heat insulating material with an organic solvent and a method of polishing the surface of the heat insulating material with an abrasive are known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the method described above, the surface of the insulation material is cleaned with an organic solvent to remove the adhesion-inhibiting layer, such as oil, from the surface of the insulation material due to its solubility in the organic solvent. However, when using organic solvents, the solvent volatilizes during the work and the removed components adhere to the wiping equipment, resulting in intermittent work such as replenishing the solvent or changing the equipment. In addition, it is difficult to maintain uniform wiping conditions, and there was a problem that excessive work was required to prevent insufficient wiping. Furthermore, when the optimal composition of the insulation for effectively removing the adhesion-inhibiting layer by wiping with a solvent conflicts with the optimal composition for heat resistance during operation of the solid rocket motor, heat resistance may be reduced to ensure manufacturability, which leads to a problem of reduced performance of the solid rocket motor.

[0006] Furthermore, the above method allows for the removal of the adhesion-inhibiting layer on the surface of the insulation material by polishing it with an abrasive. This adhesion-inhibiting layer consists of impurities or inert surfaces, and removing them exposes the active surfaces, improving adhesion to the solid propellant. However, the polishing method using abrasives presents problems: controlling the polishing thickness on the insulation material of a solid rocket motor, which is designed to be extremely thin, is very precise, and the process, including cleaning the inside of the solid rocket motor after the work, is very time-consuming.

[0007] Furthermore, both of the above methods had the problem that the way the tools were applied and the amount of force used to the insulation material of solid rocket motors, which have complex shapes, were extremely precise and complex, making automation by robots or other means difficult.

[0008] This invention has been made in view of these circumstances, and aims to provide a method for manufacturing a solid rocket motor, a surface treatment apparatus, and a surface treatment system that can stably treat the surface of a thermal insulation material. [Means for solving the problem]

[0009] The inventors of this invention conducted intensive research to solve the above problems and discovered that the problems can be solved by irradiating the thermal insulation material with atmospheric pressure plasma as a surface treatment method, leading to the present invention. In other words, the present invention is as follows. [1] A method for manufacturing a solid rocket motor, comprising a surface treatment step of irradiating the surface of insulation provided on the inner surface of the combustion vessel of the solid rocket motor with atmospheric pressure plasma. [2] A method for manufacturing a solid rocket motor according to [1], comprising a solid propellant bonding step of bonding a solid propellant to the surface of the insulation that has undergone the surface treatment step. [3] A surface treatment apparatus for treating the surface of insulation provided on the inner surface of a combustion vessel of a solid rocket motor, comprising: a plasma irradiation unit having a nozzle for irradiating plasma and an arm portion that drives the tip of the nozzle toward the insulation; an irradiation unit suspension unit having an irradiation unit moving means for moving the plasma irradiation unit; and an irradiation control unit that controls the distance between the tip of the nozzle and the surface of the insulation using the arm portion and the irradiation unit moving means. [4] The surface treatment apparatus according to [3], further comprising an adhesive spraying unit for spraying adhesive on the opposite side of the direction of movement of the plasma irradiation unit. A surface treatment system comprising: a surface treatment apparatus as described in [5][3] or [4]; a rotating platform on which the combustion vessel of the solid rocket motor is placed; and a rotation control unit for controlling the rotation of the rotating platform, wherein the plasma irradiation unit and the irradiation unit suspension unit are installed inside the combustion vessel, the plasma irradiation unit moves along the longitudinal direction of the combustion vessel, and the rotation control unit rotates the combustion vessel about the longitudinal direction as its central axis to treat the surface of the insulation inside the combustion vessel. [Effects of the Invention]

[0010] According to the manufacturing method, surface treatment apparatus, and surface treatment system of the present invention, the surface of a thermal insulation material can be stably treated. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows an example of a combustion vessel containing solid propellant for a solid rocket motor. [Figure 2] This is a schematic diagram of a surface treatment system comprising a surface treatment apparatus according to one embodiment of the present invention. [Figure 3] This is a schematic diagram of a surface treatment system equipped with a surface treatment apparatus of another embodiment. [Modes for carrying out the invention]

[0012] The manufacturing method, surface treatment apparatus, and surface treatment system of the solid rocket motor of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments.

[0013] [Manufacturing method for solid rocket motors] The present invention provides a method for manufacturing a solid rocket motor, which includes a surface treatment step of irradiating the surface of the insulation provided on the inner surface of the combustion chamber of the solid rocket motor with atmospheric pressure plasma.

[0014] (Combustion vessel for a solid rocket motor) Figure 1 shows an example of a combustion vessel 10 containing solid propellant for a solid rocket motor. The combustion vessel 10 shown in Figure 1 is constructed by providing insulation 14 on the inner surface of the case 12 that constitutes the combustion vessel 10, and adhering the solid propellant 16 to the surface of this insulation 14. Note that the nozzle and other parts are omitted in the combustion vessel 10 shown in Figure 1. According to the surface treatment step in the manufacturing method of the solid rocket motor of the present invention, the adhesion of the solid propellant 16 to the surface of the insulation 14 can be improved by irradiating the surface of the insulation 14 with atmospheric pressure plasma.

[0015] As the insulation 14 provided on the inner surface of the combustion vessel 10 of the solid rocket motor, EPDM (ethylene propylene diene rubber), silicone rubber, phenolic resin, or the like can be used. By using the above materials as the insulation 14, it is possible to suppress the transfer of heat generated in the internal space of the combustion vessel 10 to the wall surface of the combustion vessel 10. Among the above materials, EPDM is more preferable from the viewpoints of heat resistance and adhesion to the solid propellant. Further, examples of the solid propellant 16 include those obtained by mixing a high molecular polymer such as HTPB (hydroxyl-terminated polybutadiene), GAP (glycidyl azide polymer), or an elastomer mixture with an oxidizing agent such as ammonium perchlorate and a combustion aid such as aluminum powder.

[0016] (Surface Treatment Step) In the method for manufacturing a solid rocket motor of the present invention, the surface of the insulation 14 provided on the inner surface of the above combustion vessel 10 is irradiated with atmospheric pressure plasma. The atmospheric pressure plasma to be irradiated is preferably atmospheric pressure low-temperature plasma from the viewpoints of the working environment and the heat resistance of the insulation 14. Among atmospheric pressure plasmas, atmospheric pressure low-temperature plasma is generated by temporally dividing and pulsing the high-voltage application time via glow discharge or the like to the working gas, so that energy is selectively applied to electrons to ionize them and generate plasma. This atmospheric pressure low-temperature plasma is in a non-equilibrium state where the electron temperature is high, but the temperature of excited ions, non-ionized neutral atoms or molecules is low. As for the conditions of the atmospheric pressure low-temperature plasma, the electron temperature is preferably in the range of 10,000 to 100,000K, and the gas temperature is preferably in the range of 300 to 1,000K. In addition, the plasma density is 10 18 ~10 20 m -3 is preferable. Furthermore, as the working gas to be plasmatized, rare gases, molecular gases such as oxygen and nitrogen, and air which is a mixture thereof, etc., can be used. Among these, it is preferable to use oxygen or a substance containing oxygen. In surface treatment using atmospheric-pressure low-temperature plasma, oxygen radicals are particularly effective because they decompose and remove hydrocarbon-based contaminants on the insulation surface, and act on molecular chains on the insulation surface to generate functional groups such as hydroxyl groups.

[0017] By irradiating the surface of the insulation 14 with atmospheric-pressure plasma, the surface of the insulation 14 can be activated. In addition, by irradiating with atmospheric-pressure plasma, adhesion-inhibiting substances such as oils and fats on the surface of the insulation 14 can be removed. By activating the surface of the insulation 14 and removing the adhesion-inhibiting substances, the adhesive strength between the surface of the insulation 14 and the solid propellant can be increased. Examples of the adhesion-inhibiting substance include an inert layer generated during the production of the insulation, oil and fat components adhering from the external environment, and the like.

[0018] The method for manufacturing a solid rocket motor of the present invention preferably has a solid propellant bonding step of bonding the solid propellant 16 to the surface of the insulation 14 after the surface treatment step. As described above, since the surface of the insulation 14 can be activated and the adhesion-inhibiting substances can be removed by the surface treatment step, the adhesion of the solid propellant 16 can be improved by providing the solid propellant bonding step after the surface treatment step.

[0019] Furthermore, the process may include a step of applying an adhesive to the surface of the surface-treated insulation 14 between the surface treatment step and the solid propellant bonding step. Since the surface of the insulation 14 after surface treatment tends to return to an inert state over time, it is preferable to apply the adhesive promptly after the surface treatment step in order to obtain good adhesion. In addition, a primer may be applied before applying the adhesive to improve the adhesive adhesion between the insulation 14 and the solid propellant 16.

[0020] The adhesive or primer that can be used can be appropriately selected depending on the insulation 14 used, but as an example of one suitable for EPDM, Parker Lord products such as XJ-150, Chemlok 6100, Chemlok 6108, Chemlok 6126, Chemlok 6254, Chemlok 607, AP133, Y4310, Chemlok 233X, XJ-551, XJ-552, XJ-549, Chemlok 205, Chemlok 204, Chemlok 459X, and Chemlok 7701 can be used.

[0021] <Surface treatment equipment, surface treatment systems> Figure 2 is a schematic diagram of a surface treatment system 150 equipped with the surface treatment apparatus 100 of the present invention. The surface treatment apparatus 100 of the present invention is a surface treatment apparatus 100 for treating the surface of insulation 14 provided on the inner surface of a combustion vessel 10 of a solid rocket motor, and comprises a plasma irradiation unit 102 having a nozzle 104 for irradiating plasma and an arm portion 106 that drives the tip of the nozzle 104 toward the insulation 14, an irradiation unit suspension unit 110 having an irradiation unit moving means 108 for moving the plasma irradiation unit 102, and an irradiation control unit 112 that controls the distance between the tip of the nozzle 104 and the surface of the insulation 14 using the arm portion 106 and the irradiation unit moving means 108. Furthermore, the surface treatment system 150 of the present invention comprises the above-mentioned surface treatment apparatus 100, a rotating table 152 on which the combustion vessel 10 of the solid rocket motor is placed, and a rotation control unit 154 that controls the rotation of the rotating table 152. The plasma irradiation unit 102 and the irradiation unit suspension unit 110 are installed inside the combustion vessel 10. The plasma irradiation unit 102 moves along the longitudinal direction of the combustion vessel 10, and the rotation control unit 154 rotates the combustion vessel 10 with the longitudinal direction as the central axis, thereby treating the surface of the insulation 14 inside the combustion vessel 10.

[0022] (Surface treatment equipment) The surface treatment apparatus 100 of the present invention has a plasma irradiation unit 102. The plasma irradiation unit 102 includes a nozzle 104 for irradiating plasma and an arm 106 that drives the tip of the nozzle 104 toward the insulation 14. The surface treatment apparatus 100 also has an irradiation unit suspension unit 110 having an irradiation unit moving means 108 for moving the plasma irradiation unit 102. Furthermore, the surface treatment apparatus 100 has an irradiation control unit 112 that controls the distance between the tip of the nozzle 104 and the surface of the insulation 14 using the arm 106 and the irradiation unit moving means 108. The irradiation control unit 112 also controls the conditions of the plasma irradiated from the nozzle 104 of the plasma irradiation unit 102.

[0023] As shown in Figure 2, the plasma irradiation unit 102 is provided connected to an irradiation unit moving means 108 provided on the irradiation unit suspension unit 110. The irradiation unit moving means 108 can be exemplified by, for example, a rail, and the irradiation unit moving means 108 allows the plasma irradiation unit 102 to move along the irradiation unit suspension unit 110. In Figure 2, the irradiation unit suspension unit 110 is arranged along the longitudinal direction of the case 12 of the combustion vessel 10, and the plasma irradiation unit 102 is arranged to be movable along the irradiation unit suspension unit 110, that is, movable in the longitudinal direction of the case 12 of the combustion vessel 10.

[0024] The plasma irradiation unit 102 is driven by an arm 106 so that the tip of the nozzle 104 faces the insulation 14. The control of the arm 106 and the irradiation unit moving means 108 is performed by the irradiation control unit 112. The irradiation control unit 112 adjusts the distance between the tip of the nozzle 104 and the surface of the insulation 14 by controlling the arm 106 and the irradiation unit moving means 108. The distance between the tip of the nozzle 104 and the surface of the insulation 14 can be adjusted as appropriate depending on the degree of the surface to be treated, but it is preferable to adjust it so that the distance between the tip of the nozzle 104 and the surface of the insulation 14 remains constant.

[0025] A method for maintaining a constant distance between the tip of the nozzle 104 and the surface of the insulation 14 is to store the shape of the inner surface of the case 12 of the combustion container 10, or the shape of the surface of the insulation 14, in a memory unit (not shown), and then control the arm unit 106 and the irradiation unit moving means 108 according to this stored shape. Furthermore, a laser distance measuring means is provided at the tip of the nozzle 104, allowing the distance between the tip of the nozzle 104 and the surface of the insulation 14 to be adjusted while measuring the distance to the surface of the insulation 14 using a laser.

[0026] In this way, by controlling the arm portion 106 and the irradiation portion moving means 108 with the irradiation control unit 112, the tip of the nozzle 104 can be directed towards the inner surface of combustion containers 10 of various shapes or towards the insulation 14, so that the plasma irradiated from the nozzle 104 can activate the surface of the insulation 14 and remove adhesion-inhibiting substances.

[0027] Furthermore, the surface treatment system 150 of the present invention comprises the surface treatment apparatus 100, a rotating platform 152 on which the combustion vessel 10 of the solid rocket motor is placed, and a rotation control unit 154 that controls the rotation of the rotating platform 152. As described above, the irradiation unit suspension unit 110 of the surface treatment apparatus 100 is installed inside the combustion vessel 10, and the irradiation unit suspension unit 110 is installed along the longitudinal direction of the combustion vessel 10. This allows the plasma irradiation unit 102 to be moved along the longitudinal direction of the combustion vessel 10, and the plasma can be irradiated onto the insulation 14 inside the combustion vessel 10 along the longitudinal direction of the combustion vessel 10.

[0028] The rotation control unit 154 then rotates the combustion vessel 10 with its longitudinal direction as the central axis. That is, the combustion vessel 10 can be rotated with an axis parallel to the irradiation unit suspension unit 110, which is positioned along its longitudinal direction, as the central axis. After the plasma irradiation unit 102 irradiates the combustion vessel 10 with plasma along its longitudinal direction, the rotation control unit 154 rotates the combustion vessel 10. This allows the untreated insulation 14 inside the combustion vessel 10 to be positioned at the plasma irradiation position by the plasma irradiation unit 102. Then, by moving the plasma irradiation unit 102 along the longitudinal direction of the combustion vessel 10 according to the irradiation unit suspension unit 110, the insulation 14 can be irradiated with plasma along the longitudinal direction of the combustion vessel 10. Subsequently, by repeating the rotation of the combustion vessel 10 by the rotation control unit 154 and the irradiation of plasma while moving the plasma irradiation unit 102 by the irradiation control unit 112, the entire surface of the insulation 14 inside the combustion vessel 10 can be surface-treated.

[0029] (Other embodiments) Figure 3 shows a surface treatment apparatus and surface treatment system of another embodiment. Note that parts already described in Figure 2 are denoted by the same reference numerals and their descriptions are omitted. The surface treatment apparatus 200 and surface treatment system 250 of the embodiment shown in Figure 3 differ from the surface treatment apparatus 100 and surface treatment system 150 shown in Figure 2 in that the plasma irradiation unit 202 is equipped with an adhesive spraying unit 214 that sprays adhesive on the opposite side of the direction in which the plasma irradiation unit 202 moves by the irradiation unit moving means 108, and an adhesive spraying control unit 216 that controls the adhesive spraying unit 214.

[0030] According to the surface treatment apparatus 200 and surface treatment system 250 shown in Figure 3, after irradiating with plasma by the nozzle 104 of the plasma irradiation unit 202, the adhesive can be quickly applied by the adhesive spraying unit 214. Since the surface of the insulation 14 returns to an inert state over time, good adhesion can be provided by applying the adhesive quickly after plasma irradiation. Alternatively, a primer can be applied before applying the adhesive. When applying a primer, this can be done by providing a primer spraying unit instead of the adhesive spraying unit 214. In this case, the adhesive can be applied by a different method.

[0031] In Figure 3, the adhesive spraying section 214 is provided on one side of the nozzle 104 of the plasma irradiation section 202, and the device is shown in a one-way configuration where the nozzle 104 side is facing forward. However, by, for example, providing a rotation mechanism to the plasma irradiation section 202 and rotating it when it reaches one end, or by providing adhesive spraying sections 214 on both sides, the device can also be operated from both directions by irradiating with plasma and applying adhesive in the opposite direction. [Industrial applicability]

[0032] According to the present invention, the surface of the heat insulating material can be stably treated, so it can be used in the manufacture of a solid rocket motor equipped with solid propellant. It can also be used in the manufacture of a hybrid rocket having a similar structure. [Explanation of Symbols]

[0033] 10 Combustion container 12 cases 14 Insulation 16. Solid propellant 100, 200 Surface treatment equipment 102 Plasma irradiation section 104 nozzles 106 Arm section 108 Irradiation unit moving means 110 Irradiation part suspension part 112 Irradiation Control Unit 150, 250 Surface Treatment Systems 152 Rotating platform 154 Rotation Control Unit 202 Plasma irradiation section 214 Adhesive spraying section 216 Adhesive spraying control unit

Claims

1. A method for manufacturing a solid rocket motor, comprising a surface treatment step of irradiating the surface of the insulation provided on the inner surface of the combustion vessel of the solid rocket motor with atmospheric pressure plasma.

2. A method for manufacturing a solid rocket motor according to claim 1, comprising a solid propellant bonding step of bonding a solid propellant to the surface of the insulation that has undergone the surface treatment step.

3. A surface treatment apparatus for treating the surface of insulation provided on the inner surface of a combustion vessel of a solid rocket motor, A plasma irradiation unit having a nozzle for irradiating plasma and an arm portion that drives the tip of the nozzle toward the insulation, An irradiation unit suspension unit having an irradiation unit moving means for moving the plasma irradiation unit, A surface treatment apparatus comprising: an irradiation control unit that controls the distance between the tip of the nozzle and the surface of the insulation using the arm and the irradiation unit moving means.

4. The surface treatment apparatus according to claim 3, further comprising an adhesive spraying unit for spraying adhesive on the opposite side of the direction of movement of the plasma irradiation unit.

5. A surface treatment apparatus according to claim 3 or 4, A rotating platform on which the combustion vessel of the solid rocket motor is placed, The system comprises a rotation control unit that controls the rotation of the turntable, The plasma irradiation unit and the irradiation unit suspension unit are installed inside the combustion vessel, and the plasma irradiation unit moves along the longitudinal direction of the combustion vessel. The rotation control unit is a surface treatment system that processes the surface of the insulation inside the combustion vessel by rotating the combustion vessel around its longitudinal axis.

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