A device and process for bonding free standing propellant grains in an engine case

Abstract

This invention discloses an apparatus and process for bonding free-filled propellant grains inside an engine housing. The apparatus includes a base with mounting holes, a mold cylinder and a front end cap arranged within the mounting holes, forming a cavity between the front end cap and the mold cylinder. An annular protrusion is provided on the inner wall of the front end cap. By placing adhesive and the annular protrusion between the front end cap and the propellant grain, a certain gap is maintained between the propellant grain and the front end cap, allowing control over the amount of filler or adhesive used. When prefabricating the annular protrusion on the front end cap, its height can be adjusted according to different product requirements. By changing the height of the annular protrusion, the amount of adhesive used can be controlled. Furthermore, the annular protrusion better ensures uniform force distribution at the bottom of the propellant grain, resulting in accurate vertical posture of the propellant grain, thereby ensuring the reliability and consistency of the bonding. This solves the technical problem in the prior art where free-filled propellant grains cannot achieve reliable bonding and accurate posture.

Description

Technical Field

[0001] This invention belongs to the field of solid rocket engines and relates to the bonding and fixing process of free-loading propellant grains during assembly. Specifically, it relates to a device and process for bonding free-loading propellant grains inside the engine casing. Background Technology

[0002] For small and medium-sized tactical missiles, in order to achieve high thrust in a short time for rapid penetration, solid propellant grains are often designed as solid, free-loading grains due to missile caliber limitations. To reliably fix the propellant grains within the combustion chamber, a simple and feasible method is to use adhesive to bond the propellant grain head to the engine's front end cap. During bonding, the selected adhesive needs to be allowed to cure for a certain period to achieve a reliable bond. Furthermore, to ensure unobstructed airflow within the engine's combustion chamber, the propellant grains must maintain a vertical and fixed position within the combustion chamber.

[0003] Therefore, determining the appropriate process for ensuring reliable bonding of the propellant grains and guaranteeing that they are fixed in the combustion chamber according to the designed orientation is a key consideration during engine assembly. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an apparatus and process for bonding free-filled propellant grains inside an engine housing, so as to solve the technical problem that free-filled propellant grains cannot achieve reliable bonding and accurate posture in the existing technology.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] An apparatus for bonding free-filled propellant charges inside an engine housing includes a base with a mounting hole. A mold cylinder and a front end cap are disposed in the mounting hole, forming a cavity between the front end cap and the mold cylinder. An annular protrusion is provided on the inner wall of the front end cap. An adhesive is disposed on the upper surface of the front end cap, the amount of which is equal to the difference between the volume of the cavity formed by the inner surface of the front end cap, the inner wall of the mold cylinder, and the outer surface of the propellant charge, and the volume of the annular protrusion. The thickness of the adhesive is the same as the height of the annular protrusion.

[0007] This invention also includes the following technical features:

[0008] A limiting step is provided on the bottom inner wall of the mold cylinder, and the inner wall of the limiting step is fixedly connected to the outer wall of the front end cap.

[0009] The inner wall of the limiting step and the outer wall of the front end cap are connected by threads.

[0010] A limiting protrusion is provided on the outer wall of the mold cylinder.

[0011] The mounting hole of the base is threadedly connected to the mold cylinder.

[0012] The adhesive is a two-component epoxy resin adhesive.

[0013] A process for bonding free-filled propellant charges within an engine housing, based on the aforementioned apparatus for bonding free-filled propellant charges within an engine housing, includes the following steps:

[0014] Step 1: Determine the type of propellant charge. Based on the outer diameter and length of the propellant charge, determine the inner diameter and length of the mold cylinder. Based on the head profile of the propellant charge, determine the inner profile of the front end cap.

[0015] Step 2: Based on the inner diameter of the mounting hole determined by the outer diameter of the mold cylinder, connect the mold cylinder and the front end cap base to the mold cylinder, and assemble the mold cylinder and the front end cap.

[0016] Step 3: Pour a certain amount of the mixed adhesive into the front end cap, and then vertically insert the drug column into the cavity formed by the front end cap and the mold cylinder from above, until the head of the drug column contacts the annular protrusion on the front end cap.

[0017] Step four: After standing for a period of time and the adhesive has cured, remove the base and the mold cylinder to obtain a reliably bonded and uniformly oriented catalytic column and front end cap.

[0018] The propellant grain is a composite propellant with a length-to-diameter ratio greater than 100%, and the lower axial end of the propellant grain is butterfly-shaped.

[0019] The entire drug grain, except for its axial upper end face, is covered with a coating layer.

[0020] The coating layer is EPDM rubber.

[0021] Compared with the prior art, the beneficial technical effects of this invention are:

[0022] (I) In this invention, an adhesive and annular protrusion are provided between the front end cap and the propellant column. The annular protrusion ensures that there is a certain gap between the propellant column and the front end cap, which is used to control the amount of filler or adhesive. When the annular protrusion is prefabricated on the front end cap, its height can be adjusted according to different product requirements. By changing the height of the annular protrusion, the amount of adhesive used can be controlled. In addition, the annular protrusion can better ensure that the force at the bottom of the propellant column is uniform, so that the vertical posture of the propellant column is accurate, thereby ensuring the reliability and quality consistency of the bonding, and solving the technical problem that the free-filling propellant column in the prior art cannot achieve reliable bonding and accurate posture.

[0023] (II) The device of the present invention is applicable to the bonding of all small, high aspect ratio free-filling propellant grains. The size of the base and the mold cylinder can be designed according to the propellant grain shape. The bonding posture of the propellant grain can be controlled by the gap between the mold cylinder and the propellant grain, which improves the versatility of the device. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0025] Figure 2 This is a partially enlarged view of the present invention;

[0026] Figure 3 This is a schematic diagram of the front end cap of the present invention;

[0027] Figure 4 This is a schematic diagram of the structure of the mold cylinder of the present invention.

[0028] The meanings of the labels in the diagram are as follows: 1. Base, 2. Mold cylinder, 3. Front end cap, 5. Medicated column, 4. Adhesive, 6. Mounting hole, 7. Limiting step, 8. Limiting protrusion, 9. Annular protrusion, 10. Covering layer.

[0029] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, all components in this invention are those known in the art.

[0031] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0032] This invention provides a device for bonding free-filling propellant charges inside an engine housing, comprising a base 1, a mounting hole 6 on the base 1, a mold cylinder 2 and a front end cap 3 disposed in the mounting hole 6, forming a cavity between the front end cap 3 and the mold cylinder 2; an annular protrusion 9 disposed on the inner wall of the front end cap 3; an adhesive 4 disposed on the upper surface of the front end cap 3, the amount of adhesive 4 being equal to the difference between the volume of the cavity formed by the inner surface of the front end cap 3, the inner wall of the mold cylinder 2 and the outer surface of the propellant charge 5 and the volume of the annular protrusion 9; the thickness of the adhesive 4 being the same as the height of the annular protrusion 9.

[0033] In the above technical solution, an adhesive 4 and an annular protrusion 9 are provided between the front end cap 3 and the propellant 5. The annular protrusion 9 ensures that a certain gap is left between the propellant 5 and the front end cap 3, which is used to control the amount of filler or adhesive. The height of the annular protrusion 9 can be adjusted according to different process requirements. By adjusting the height of the annular protrusion 9, the amount of adhesive 4 used can be controlled. In addition, the annular protrusion 9 can better ensure that the force at the bottom of the propellant 5 is uniform, so that the vertical posture of the propellant 5 is accurate, thereby ensuring the reliability and quality consistency of the bonding, and solving the technical problem that the free-filling propellant 5 in the prior art cannot achieve reliable bonding and accurate posture.

[0034] Preferably, the base 1 is made of No. 45 steel, and an appropriate diameter and thickness are selected to keep the center of gravity of the entire device low, ensuring that the device does not flip or shift during the bonding process; the front end cap 3 is made of 30CrMnSiA alloy steel.

[0035] A limiting step 7 is provided on the bottom inner wall of the mold cylinder 2, and the inner wall of the limiting step 7 is fixedly connected to the outer wall of the front end cap 3.

[0036] In the above technical solution, the limiting step 7 is used for axial limiting to ensure that the base 1 and the mold cylinder 2 are assembled in place.

[0037] The inner wall of the limiting step 7 is threadedly connected to the outer wall of the front end cap 3.

[0038] A limit ring 8 is provided on the outer wall of the mold cylinder 2.

[0039] In the above technical solution, the limiting protrusion 8 is used to limit the axial displacement between the mold cylinder 2 and the base 1.

[0040] The mounting hole 6 of the base 1 is threadedly connected to the mold cylinder 2.

[0041] Adhesive 4 is a two-component epoxy resin adhesive.

[0042] In the above technical solution, the two components of adhesive 4 are mixed in a 1:1 ratio, and after bonding is completed using adhesive 4, it needs to stand for 4 hours for curing.

[0043] This invention also provides a process for bonding free-filled propellant charges within an engine housing, based on an apparatus for bonding free-filled propellant charges within an engine housing, comprising the following steps:

[0044] Step 1: Determine the type of the propellant 5, determine the inner diameter and length of the mold cylinder 2 based on the outer diameter and length of the propellant 5, and determine the inner surface of the front end cap 3 based on the head surface of the propellant 5.

[0045] Step 2: Based on the inner diameter of the mounting hole 6 determined by the outer diameter of the mold cylinder 2, connect the mold cylinder 2 and the base 1 of the front end cap 3 to the mold cylinder 2, and assemble the mold cylinder 2 and the front end cap 3.

[0046] Step 3: Pour a certain amount of the mixed adhesive 4 into the front end cap 3, and then vertically insert the drug column 5 from above the mold cylinder 2 into the cavity formed by the front end cap 3 and the mold cylinder 2 until the head of the drug column 5 contacts the annular protrusion 9 on the front end cap 3.

[0047] Step 4: After standing for a period of time and the adhesive 4 has cured, remove the base 1 and the mold cylinder 2 to obtain the drug column 5 and the front end cap 3 with reliable adhesion and consistent posture.

[0048] In the above technical solution, when calculating and determining the amount of adhesive 4, the inner surface of the front end cap 3 is obtained based on the outer surface of the propellant 5. Then, based on the height of the annular protrusion 9, a cavity is formed between the inner surface of the front end cap 3, the inner wall of the mold cylinder 2, and the outer surface of the propellant 5. The volume of the cavity formed by the inner surface of the front end cap 3, the inner wall of the mold cylinder 2, and the outer surface of the propellant 5 is obtained using 3D modeling software such as SolidWorks. Then, the volume of the annular protrusion 9 is subtracted to obtain the amount of adhesive 4. The volume of the annular protrusion 9 is equal to the difference between the volume of the cylinder with the outer wall of the annular protrusion 9 as its radius and the volume of the cylinder with the inner wall of the annular protrusion 9 as its radius, which is also obtained using 3D modeling software such as SolidWorks.

[0049] In step three, when the drug cartridge 5 is vertically inserted from above the mold cylinder 2 into the cavity formed by the front end cap 3 and the mold cylinder 2, and the head of the drug cartridge 5 contacts the annular protrusion 9 on the front end cap 3, due to the downward pressure of the drug cartridge 5, the adhesive 4 on the front end cap 3 moves radially outward, thereby filling the cavity formed by the drug cartridge 5, the mold cylinder 2, the front end cap 3 and the annular protrusion 9.

[0050] The propellant grain 5 is a composite propellant with an aspect ratio greater than 7, and the lower axial end of the propellant grain 5 is butterfly-shaped.

[0051] In the above technical solution, when the length-to-diameter ratio of the propellant 5 is greater than 7, the thickness of the adhesive 4 (i.e., the annular protrusion 9) is generally 2mm ± 0.2mm.

[0052] Except for its axial upper end face, the entire propellant column 5 is provided with a coating layer 10.

[0053] In the above technical solution, the thickness of the coating layer 10 can be designed according to requirements, and the coating layer 10 plays a role in limiting combustion during engine operation.

[0054] The coating layer 10 is made of EPDM rubber.

[0055] In the above technical solution, EPDM rubber can meet the process requirements.

Claims

1. A device for bonding free-loading propellant charges inside an engine housing, characterized in that, Includes a base (1), on which a mounting hole (6) is provided, in which a mold cylinder (2) and a front end cap (3) are provided, and a cavity is formed between the front end cap (3) and the mold cylinder (2); an annular protrusion (9) is provided on the inner wall of the front end cap (3); an adhesive (4) is provided on the upper surface of the front end cap (3), and the amount of the adhesive (4) is equal to the difference between the volume of the cavity formed by the inner surface of the front end cap (3), the inner wall of the mold cylinder (2) and the outer surface of the precipitate (5) and the volume of the annular protrusion (9); the thickness of the adhesive (4) is the same as the height of the annular protrusion (9).

2. The apparatus for bonding freely loaded propellant charges within an engine housing as described in claim 1, characterized in that, A limiting step (7) is provided on the bottom inner wall of the mold cylinder (2), and the inner wall of the limiting step (7) is fixedly connected to the outer wall of the front end cap (3).

3. The apparatus for bonding freely loaded propellant charges within an engine housing as described in claim 2, characterized in that, The inner wall of the limiting step (7) and the outer wall of the front end cap (3) are connected by threads.

4. The apparatus for bonding freely loaded propellant charges within an engine housing as described in claim 1, characterized in that, A limiting protrusion ring (8) is provided on the outer wall of the mold cylinder (2).

5. The apparatus for bonding freely loaded propellant charges within an engine housing as described in claim 1, characterized in that, The mounting hole (6) of the base (1) is threadedly connected to the mold cylinder (2).

6. The apparatus for bonding free-loading propellant charges within an engine housing as described in claim 1, characterized in that, The adhesive (4) is a two-component epoxy resin adhesive.

7. A process for bonding free-loading propellant charges inside an engine housing, characterized in that, The apparatus for bonding free-filled propellant charges within an engine housing, as described in any one of claims 1 to 6, comprises the following steps: Step 1: Determine the type of the precipitate (5), determine the inner diameter and length of the mold cylinder (2) based on the outer diameter and length of the precipitate (5), and determine the inner surface of the front end cap (3) based on the head surface of the precipitate (5); Step 2: Based on the inner diameter of the mounting hole (6) determined by the outer diameter of the mold cylinder (2), connect the mold cylinder (2) and the base (1) of the front end cap (3) to the mold cylinder (2), and assemble the mold cylinder (2) and the front end cap (3); Step 3: Pour a certain amount of the mixed adhesive (4) into the front end cap (3), and then vertically place the drug column (5) from above the mold cylinder (2) into the cavity formed by the front end cap (3) and the mold cylinder (2) until the head of the drug column (5) contacts the annular protrusion (9) on the front end cap (3); Step 4: After standing for a period of time and the adhesive (4) has cured, remove the base 1 and the mold (2) to obtain a drug column (5) with reliable adhesion and consistent posture and the front end cap (3).

8. The process for bonding free-loading propellant charges within an engine housing as described in claim 7, characterized in that, The propellant grain (5) is a composite propellant with an aspect ratio greater than 7, and the lower axial end of the propellant grain (5) is butterfly-shaped.

9. The process for bonding free-loading propellant charges within an engine housing as described in claim 7, characterized in that, The drug column (5) is provided with a coating layer (10) except for its axial upper end face.

10. The process for bonding free-loading propellant charges within an engine housing as described in claim 9, characterized in that, The coating layer (10) is EPDM rubber.

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