Bidirectional manufacturing device and method for grain preparation

Abstract

The invention relates to the field of grain manufacturing, in particular to density optimization design in the grain manufacturing process. According to the two-way manufacturing device and method for grain preparation, the two-way stamping technology is adopted, pressure attenuation caused by die wall friction is effectively overcome, accordingly, the axial and radial density uniformity of the grain is remarkably improved, and the forming capacity and quality consistency of the complex special-shaped grain are greatly improved through the technology. The two-way manufacturing device for grain preparation comprises a mold and an upper punch, the mold comprises a grain pressing cavity used for containing grain powder and further comprises a lower punch, the mold comprises an upper sliding way providing a sliding space for the upper punch and a lower sliding way providing a sliding space for the lower punch, and the upper sliding way, the lower sliding way and the grain pressing cavity are communicated.

Description

Technical Field

[0001] This invention relates to the field of drug column manufacturing, and more specifically to density optimization design in the drug column manufacturing process. Background Technology

[0002] A propellant charge is a solid energetic component with a predetermined geometry and density, formed by mixing high explosives, such as RDX and octogen, with components such as polymer binders and plasticizers through specific processes such as pressing or casting. Its applications are wide-ranging, including both military and civilian fields. Examples include oilfield perforation shells, mine blasting, special blasting, and pyrotechnic devices on spacecraft.

[0003] In existing technologies, the process for preparing press-loaded explosive charges involves unidirectional stamping. Weighed, loose explosive powder is poured into a pre-formed mold. Driven by a press, the upper punch applies high pressure along a single axis to the explosive powder within the mold.

[0004] However, while this technical solution can conveniently and efficiently prepare explosive charges, it has the following technical drawbacks: First, when subjected to mechanical impact, thermal stimulation, or high-speed impact, the explosive charges are prone to premature detonation, such as chamber explosion, posing a serious safety hazard to production, transportation, and use. Second, during detonation, the propagation of the combustion wave is unstable and uncontrollable, making it difficult to achieve the intended effect and affecting the accuracy and reliability of the explosion system.

[0005] Furthermore, there are irregularly shaped propellant grains, which refer to propellant grains with non-circular cross-sections or complex geometric shapes along the axial direction. These types of propellant grains are typically designed to meet specific tactical and technical specifications such as energy release patterns, spatial layout, or aerodynamic shape. The aforementioned technical deficiencies are even more pronounced in irregularly shaped propellant grains. Summary of the Invention

[0006] The purpose of this invention is to provide a bidirectional fabrication apparatus and method for propellant grain preparation. Employing bidirectional stamping technology, it effectively overcomes pressure attenuation caused by mold wall friction, thereby significantly improving the axial and radial density uniformity of the propellant grain. This directly enhances the stability and reliability of the propellant grain's detonation performance. Simultaneously, due to the uniform internal stress distribution, it greatly reduces the risk of structural defects such as cracks and delamination, ensuring safety in production and use. Most importantly, this technology significantly improves the forming capability and quality consistency of complex, irregularly shaped propellant grains, overcoming the technical bottlenecks that traditional unidirectional pressing methods struggle to achieve.

[0007] The present invention is achieved through the following technical solution: a bidirectional manufacturing apparatus for preparing drug particles, comprising a mold and an upper punch, the mold comprising a pressing chamber for placing drug powder, and a lower punch, the mold comprising an upper slide rail providing sliding space for the upper punch and a lower slide rail providing sliding space for the lower punch, the upper slide rail, the lower slide rail and the pressing chamber being interconnected, the upper punch being configured to provide a downward pressing action to the drug powder in the pressing chamber from top to bottom, and the lower punch being configured to provide an upward pressing action to the drug powder in the pressing chamber from bottom to top.

[0008] As a preferred embodiment of the present invention, the mold comprises an independent upper mold and a lower mold, wherein the upper punch is slidably connected to the upper mold and the lower punch is slidably connected to the lower mold.

[0009] As a preferred embodiment of the present invention, two pressure pads are provided below the lower die, and the thickness of the two pressure pads is configured to be consistent with the stroke of the lower punch during the upper pressing action.

[0010] As a preferred embodiment of the present invention, an ejector pad is provided below the lower die, and the thickness of the ejector pad is configured to be consistent with the stroke of the lower punch during the powder removal action.

[0011] As a preferred embodiment of the present invention, the upper punch includes an upper limit plate for abutting against the upper surface of the mold and an upper punch head connected to the upper limit plate, and the lower punch includes a lower limit plate for abutting against the lower surface of the mold and a lower punch head connected to the lower limit plate.

[0012] As a preferred embodiment of the present invention, it further includes a powder-removing sleeve connected to the lower mold, the powder-removing sleeve including a drug-taking chamber, the drug-taking chamber being configured such that when the powder pressing process is completed, the lower punch pushes the drug column into the drug-taking chamber.

[0013] As a preferred embodiment of the present invention, the lower mold includes an inwardly recessed inner body, and the upper mold includes an outer buckle for engaging with the inner body to form a snap and fixation.

[0014] As a preferred embodiment of the present invention, the material strength of the mold is greater than that of the upper punch and the lower punch.

[0015] A bidirectional fabrication method for preparing propellant columns, comprising the aforementioned bidirectional fabrication apparatus for preparing propellant columns, wherein the method comprises:

[0016] Place the medicine powder into the compression chamber;

[0017] The powder pressing action is completed by the upper punch and the lower punch respectively pressing the powder downwards and upwards.

[0018] The powdered medicine was formed into pills;

[0019] Remove the medicinal column from the mold.

[0020] As a preferred embodiment of the present invention, the mold, the upper punch, and the lower punch are preheated before the powder pressing action begins.

[0021] In summary, the present invention has the following beneficial effects:

[0022] 1. By configuring the upper and lower punches that can move relative to each other, the powder is subjected to pressure in both directions, which effectively overcomes the axial pressure attenuation caused by the friction of the mold wall. This fundamentally solves the problem of axial density gradient of the propellant caused by traditional unidirectional compression, and significantly improves the uniformity of the propellant density, the stability of detonation performance and the safety of use.

[0023] 2. The separate upper and lower mold structure greatly simplifies the machining process of the mold and reduces manufacturing difficulty and cost. At the same time, this structure facilitates the disassembly and maintenance of the mold, as well as the independent replacement and maintenance of each component, improving the maintainability and service life of the equipment.

[0024] 3. By setting a double pressure pad of a specific thickness, the final stroke and position of the lower punch during the upper pressing action are precisely controlled, making the process parameters controllable and repeatable.

[0025] 4. By setting an ejection pad of a specific thickness, a controllable and stable ejection stroke is provided for the lower punch. This design can safely and completely eject the molded cartridge from the mold cavity, effectively avoiding chipping, breakage, or internal damage to the cartridge caused by uneven force or sudden impact during the demolding process, thus ensuring product quality and operational safety.

[0026] 5. A dedicated powder removal sleeve and drug extraction cavity are provided to offer a protected containment space for the ejection process of the formed drug cartridge. The removal of the drug cartridge is simpler and more controllable, avoiding direct collision between the drug cartridge and the hard platform, reducing human contact, and protecting the integrity of the drug cartridge.

[0027] 6. The upper and lower molds are connected by the cooperation of the inner concave body and the outer buckle body, which ensures the precise positioning and tight connection between the two modules during the pressing process, and guarantees the overall rigidity of the mold and the forming quality.

[0028] 7. The material strength of the mold body is higher than that of the upper and lower punches, ensuring that the mold, as the forming cavity, has optimal resistance to deformation and wear under extremely high pressing pressure. This maximizes the consistency of batch production dimensions of the propellant grains and extends the service life of the mold.

[0029] 8. The preheating process can reduce the temperature difference between the powder and the metal mold, and reduce the risk of the powder absorbing moisture from the air and condensing due to contact with the cold mold surface. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of Example 1, showing the initial state;

[0031] Figure 2 yes Figure 1 A magnified view of the details at point b in the image;

[0032] Figure 3 yes Figure 1 A schematic diagram after the powder is pressed and compressed;

[0033] Figure 4 yes Figure 1 A schematic diagram after the powder has been pressed and compressed.

[0034] Figure 5 yes Figure 1 A diagram illustrating the process of removing powder after pressing.

[0035] In the diagram: 1. Mold, 11. Upper mold, 12. Lower mold, 13. Pressing chamber, 14. Upper slide, 15. Lower slide, 16. Outer buckle, 17. Inner recess, 2. Upper punch, 21. Upper limit plate, 22. Upper punch head, 3. Lower punch, 31. Lower punch head, 32. Lower limit plate, 4. Second pressure pad, 5. Ejection pad, 6. Powder removal sleeve, 61. Medicine removal chamber, a. Medicine powder. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to the accompanying drawings.

[0037] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

[0038] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this specification. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0039] This embodiment details a bidirectional fabrication apparatus for preparing propellant grains and its operating method. Please refer to [link to relevant documentation]. Figure 1 The device mainly includes mold 1, upper punch 2, lower punch 3, two pressure pads 4, and ejection pad 5.

[0040] First, the device is in such a position Figure 1The initial state is shown. At this point, the upper punch 2 is raised to its highest point, and the lower punch 3 is lowered to its lowest point, leaving sufficient space for the powder filling. The operator accurately weighs the pre-mixed powder according to the formula, for example, a mixed explosive powder based on RDX or octogen, and pours it into the pressing chamber 13 formed by the mold 1. During this stage, the upper slide 14 and the lower slide 15 remain unobstructed to ensure that there is no interference with subsequent pressing actions.

[0041] Before the powder pressing process begins, mold 1, upper punch 2, and lower punch 3 can be preheated. The preheating temperature is usually controlled between 60°C and 80°C, and can be adjusted according to the characteristics of the binder in the powder formulation. The purpose of preheating is twofold: firstly, to reduce the temperature difference between the room-temperature powder and the metal mold, preventing the powder from absorbing moisture from the air and condensing due to contact with a cold surface, thus ensuring the dryness of the powder and the quality of the molding; secondly, appropriate preheating helps certain polymer binders to produce microplastic flow during the pressing process, further improving the density and internal bonding of the powder pellets.

[0042] In terms of material selection, mold 1, as the core forming component bearing high pressure, requires high material strength. High-hardness, high-wear-resistant alloy tool steel, such as Cr12MoV or high-speed steel, is preferred, and it undergoes quenching and multiple tempering treatments to ensure its resistance to deformation and wear under repeated high pressure, maintaining the dimensional accuracy of the compression chamber 13 for a long time. In contrast, the upper punch 2 and lower punch 3, as force-applying components, can have slightly lower material strength than mold 1, provided sufficient strength is ensured. Bearing steel such as GCr15 or other high-quality carbon tool steel can be selected. This gradient design in material strength ensures that the mold, as the forming chamber, has optimal resistance to deformation and wear under extremely high pressing pressure. This maximizes the consistency of the batch production dimensions of the propellant grains and the service life of the mold.

[0043] like Figure 1 and Figure 2 As shown, mold 1 adopts a split design, consisting of an independent upper mold 11 and a lower mold 12. The upper punch 2 is slidably connected to the upper mold 11, and the lower punch 3 is slidably connected to the lower mold 12. This split structure greatly simplifies the mold's machining process. Compared to an integral mold, the difficulty and cost of machining deep holes required for independent upper and lower molds are significantly reduced. At the same time, this structure facilitates mold disassembly, maintenance, and independent replacement and maintenance of each component, improving the maintainability and service life of the equipment.

[0044] To ensure precise alignment and prevent misalignment between the upper mold 11 and the lower mold 12 during high-pressure pressing, this invention incorporates a positioning structure. (See also...) Figure 2The enlarged view shows that the lower mold 12 includes an inwardly recessed inner body 17, while the upper mold 11 includes an outer snap-fit ​​body 16 that engages with the inner body 17 to form a lock and fixation. During mold closing, the outer snap-fit ​​body 16 embeds into the inner body 17, forming a tight conical or inclined surface fit. This achieves precise horizontal positioning and a tight vertical connection between the upper and lower molds, ensuring the overall rigidity of the mold and the dimensional accuracy of the formed propellant cartridge.

[0045] The powder pressing action is the core of this invention, which is divided into two actions: downward pressing and upward pressing. The two work together to overcome the friction of the mold wall.

[0046] See Figure 3 , Figure 3 This is the downward pressing action of the powder pressing process. An external press drives the upper punch 2 to move downwards along the upper slide 14. The upper limit plate 21 of the upper punch 2 eventually contacts the upper surface of the mold 1, thereby precisely controlling the end point of the downward pressing stroke. During this process, the upper punch 22 applies strong downward pressure to the powder a in the pressing chamber 13, performing initial compression. In this stage, the secondary pressure pad 4 and the ejection pad 5 are both installed on the lower surface of the mold 12.

[0047] See Figure 4 , Figure 4 This is the upward pressing action of the powder pressing process. In this stage, the secondary pressure pad 4 has been removed, leaving only the ejector pad 5. The external press drives the lower punch 3 to move upward along the sliding track 15. The thickness of the secondary pressure pad 4 is configured to perfectly match the designed stroke of the lower punch 3 during the upward pressing action. When the lower limit plate 32 of the lower punch 3 contacts the upper surface of the secondary pressure pad 4, the upward pressing action reaches the preset endpoint, thereby precisely controlling the magnitude and point of application of the upward pressure. The lower punch 31 applies upward pressure to the powder a.

[0048] In existing technologies, the unidirectional stamping process, due to its inherent limitations, results in uneven charge density distribution. During the stamping process, intense friction occurs between the powder particles and the inner wall of the die. This leads to significant pressure attenuation during axial transmission. Consequently, the density is highest at the tip of the propellant near the upper punch, decreasing towards the bottom, creating a significant axial density gradient. This density inhomogeneity directly results in inconsistent mechanical strength and detonation performance of the propellant charge along the axial direction.

[0049] Density is a core factor affecting key performance parameters of explosives, such as detonation velocity and detonation pressure. An axial density gradient makes the propagation of the combustion wave during detonation unstable and uncontrollable, making it difficult to achieve the intended destructive effect and impacting the accuracy and reliability of weapon systems. Areas with uneven density, especially low-density regions, become structural weak points in the explosive charge. Under mechanical impact, thermal stimulation, or high-speed impact, these areas are more prone to forming hotspots, significantly increasing the risk of premature detonation and posing serious safety hazards to production, transportation, and use.

[0050] Unidirectional pressing is poorly suited for irregularly shaped propellant charges. In irregular cross-sections, such as sharp corners, thin walls, or complex surfaces, powder filling and flow become more difficult. During unidirectional pressing, pressure attenuation is more severe in these geometrically discontinuous regions, leading to significant local density differences. Sharp corners may become over-compacted due to stress concentration, while thin-walled areas far from the direction of pressure application may be under-compacted, resulting in looseness or cracks. Due to the extremely uneven density distribution in three-dimensional space, the detonation wave propagation path of irregularly shaped propellant charges becomes exceptionally complex and unpredictable, failing to achieve their designed special functions, such as directional detonation or controllable detonation waveforms, thus completely negating the original intent of the irregular design.

[0051] In this case, through the aforementioned bidirectional simultaneous or sequential pressing action, powder a is subjected to pressure from both the upper and lower directions within the pressing chamber 13. This design fundamentally counteracts the axial pressure attenuation caused by intense friction between the powder and the mold wall during unidirectional pressing. Its direct benefit is a significant improvement in the axial and radial density uniformity of the propellant grain, eliminating the inherent density gradient problem of traditional unidirectional pressing, resulting in a denser internal structure and more uniform stress distribution. This not only significantly enhances the reliability and stability of the propellant grain's detonation performance but also greatly reduces the risk of structural defects such as cracks and delamination caused by uneven density, ensuring safety during subsequent transportation, storage, and use. This technology is particularly advantageous for irregularly shaped propellant grains with non-circular cross-sections or complex axial geometries, solving the technical bottleneck of traditional unidirectional pressing's difficulty in forming high-quality irregularly shaped propellant grains.

[0052] After the powder pressing process is completed, powder a has been formed into a dense column within the pressing cavity 13. The next step is the demolding and powder removal process, see below. Figure 5 .

[0053] In this step, both the secondary pressure pad 4 and the ejector pad 5 have been removed. The thickness of the ejector pad 5 is configured to match the stroke required by the lower punch 3 when ejecting the bolus. The external press drives the lower punch 3 upward again, i.e., the ejection action. When the lower limit plate 32 contacts the ejector pad 5, the lower punch 31 smoothly and completely ejects the formed bolus. The user only needs to remove the bolus from the pressure chamber 13. The setting of the ejector pad 5 avoids excessive or insufficient ejection stroke, ensuring a smooth and controllable ejection process, and effectively preventing edge chipping, breakage, or internal damage to the bolus due to sudden impact or uneven force at the moment of demolding.

[0054] To further ensure the safety and convenience of cartridge removal, the device is also equipped with a powder removal sleeve 6. The powder removal sleeve 6 is reliably connected to the lower die 12 via threads or flanges. The powder removal sleeve 6 has a cartridge removal chamber 61 inside. When the cartridge is ejected by the lower punch 3, it is not directly exposed to the outside, but is safely delivered into the cartridge removal chamber 61. The operator can then remove the cartridge from the cartridge removal chamber 61. This design avoids direct collision between the cartridge and the hard platform, reduces the risk of direct human contact with the cartridge, provides an additional safety barrier for the operator, and also helps protect the smoothness and integrity of the cartridge surface.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Furthermore, the terms "vertical," "horizontal," "front," and "rear," etc., mentioned in the embodiments of the present invention indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. These are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. It should be further noted that, unless otherwise explicitly specified and limited, terms such as "install," "connect," "join," and "fix" in the description should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0056] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A bidirectional manufacturing apparatus for preparing medicinal powder, comprising a mold (1) and an upper punch (2), said mold (1) comprising a pressing chamber (13) for placing medicinal powder, characterized in that: It also includes a lower punch (3). The mold (1) includes an upper slide (14) that provides sliding space for the upper punch (2) and a lower slide (15) that provides sliding space for the lower punch (3). The upper slide (14), the lower slide (15) and the pressing chamber (13) are connected. The upper punch (2) is configured to provide a downward pressing action to the powder in the pressing chamber (13) from top to bottom. The lower punch (3) is configured to provide an upward pressing action to the powder in the pressing chamber (13) from bottom to top.

2. The bidirectional fabrication apparatus for preparing drug cartridges according to claim 1, characterized in that: The mold (1) includes an independent upper mold (11) and a lower mold (12), the upper punch (2) is slidably connected to the upper mold (11), and the lower punch (3) is slidably connected to the lower mold (12).

3. The bidirectional fabrication apparatus for preparing drug cartridges according to claim 2, characterized in that: A second pressure pad (4) is provided below the lower die (12), and the thickness of the second pressure pad (4) is configured to be consistent with the stroke of the lower punch (3) in the upper pressing action.

4. The bidirectional fabrication apparatus for preparing drug cartridges according to claim 2, characterized in that: An ejector block (5) is provided below the lower die (12), and the thickness of the ejector block (5) is configured to be consistent with the stroke of the lower punch (3) in the powder removal action.

5. The bidirectional fabrication apparatus for preparing drug cartridges according to claim 1, characterized in that: The upper punch (2) includes an upper limit plate (21) for contacting the upper surface of the mold (1) and an upper punch (22) connected to the upper limit plate (21), and the lower punch (3) includes a lower limit plate (32) for contacting the lower surface of the mold (1) and a lower punch (31) connected to the lower limit plate (32).

6. The bidirectional fabrication apparatus for preparing drug cartridges according to claim 2, characterized in that: It also includes a powder removal sleeve (6) connected to the lower mold (12), the powder removal sleeve (6) including a medicine taking chamber (61), the medicine taking chamber (61) being configured such that when the powder pressing process ends, the lower punch (3) pushes the medicine column into the medicine taking chamber (61).

7. The bidirectional fabrication apparatus for preparing drug cartridges according to claim 2, characterized in that: The lower mold (12) includes an inwardly recessed inner body (17), and the upper mold (11) includes an outer buckle (16) for engaging with the inner body (17) to form a snap and fix.

8. The bidirectional fabrication apparatus for preparing drug cartridges according to claim 1, characterized in that: The material strength of the mold (1) is greater than that of the upper punch (2) and the lower punch (3).

9. A bidirectional fabrication method for preparing drug columns, comprising the bidirectional fabrication apparatus for preparing drug columns as described in any one of claims 1-8, characterized in that: The method includes: Place the powdered medicine into the compression chamber (13); The powder pressing action is completed by the upper punch (2) and the lower punch (3) pressing the powder downward and upward respectively; The powdered medicine was formed into pills; Remove the drug cartridge from the mold (1).

10. The bidirectional preparation method for preparing drug cartridges according to claim 9, characterized in that: Before the powder pressing action begins, the mold (1), the upper punch (2) and the lower punch (3) are preheated.

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