Two-way combined group module precision pressing process

Abstract

This invention discloses a two-way combined group-mode precision compression process, including the following steps: Step (1): Explosive preparation, optimizing the explosive formula, improving the physicochemical properties of the explosive particles, utilizing reasonable particle gradation and explosive crystal spheroidization technology to reduce the porosity between explosive particles, and secondly, using highly dense spheroidized black oxojin and octogen high-energy explosive particles with smooth surfaces and shapes as close to circles as possible to reduce crystal defects and improve crystal density and compressibility. The process of this invention achieves precise clustering and two-way compression of multiple explosive columns on a conventional upward-moving unidirectional press, which is economical, widely applicable, and highly efficient. The prepared explosive columns have the advantages of large aspect ratio (≥2), high density and uniform distribution (density difference ≤0.5%), high energy, and good quality.

Description

Technical Field

[0001] This invention belongs to the field of explosive preparation technology, specifically relating to a two-way combined multi-mode precision compression process. Background Technology

[0002] Warhead explosive loading refers to processing explosives into propellant columns with a specific shape, strength, and density, and fixing them inside the warhead; alternatively, explosives can be directly loaded into the warhead and processed into a suitable charge. The former is called "indirect loading," and the latter is called "direct loading." Currently, commonly used loading methods include: compression loading, casting loading, step-compression loading, plastic loading, and casting loading. Compression loading involves using molds and presses to compress granular explosives into propellant columns of the required shape and size, or directly pressing them into the warhead chamber. Depending on the order in which the explosives are loaded into the chamber, it can be divided into two forms: step-compression loading (indirect compression loading) and direct compression loading. Step-compression loading involves loading a fixed quantity of granular explosives into a special mold (see...). Figure 1 The explosive is compressed into a specific shape and density within the projectile's chamber, and then the explosive is loaded into the chamber and secured with adhesives or other methods. For projectiles that are difficult to directly compress or have long chambers, as well as for fuse detonator tubes and diffuser tubes, the explosive is typically loaded using a separate explosive charge method.

[0003] A wide variety of explosives can be used with the compression loading method, meaning that this method is highly adaptable to various explosives, especially high-energy explosives that have undergone desensitization treatment. Explosives suitable for compression loading include TNT, tertrol, desensitized RDX, desensitized aluminum, desensitized Tyan, and polymer-bonded explosives primarily composed of RDX and octogen. Compression-loaded explosive charges have better detonation sensitivity than injection-loaded charges. Therefore, compression loading remains a major charging method. Many types of ammunition are loaded using compression loading, ranging from very small detonators, percussion caps, and delay powder cakes to small and medium caliber grenades, armor-piercing projectiles, shaped charge projectiles, and various detonation charge elements. The widespread use of compression loading demonstrates its indispensable and important charging method.

[0004] Depending on the direction of pressure application during charging, the charging method can be further divided into unidirectional charging and bidirectional charging. Unidirectional charging involves a punch applying pressure to the explosive (see...). Figure 2 ( ), while bidirectional pressurization involves two punches applying pressure to the explosive from two directions (see...) Figure 3 If the ratio of the height to the diameter of the compressed propellant is greater than 2, bidirectional compression is required. This reduces the axial density difference of the propellant and increases its strength. The base of the bidirectional compression mold is designed as a downward punch. During compression, the upward and downward punches serve the same purpose, applying essentially the same pressure to both ends of the propellant.

[0005] When pressing a large number of drug pellets, individual molds are often combined to improve production efficiency, resulting in a combined mold (group mold). The number of drug pellets that can be pressed at one time needs to be calculated based on the pressure required to press a single pellet and the total pressure of the press. The combined mold can be directly integrated into the drug pressing trolley. Figure 4 This is a schematic diagram of a traditional combined mold (group mold) bidirectional drug pressing trolley structure, mainly used on ordinary downward-moving unidirectional hydraulic presses.

[0006] Regardless of the type of compression loading method, the equipment used is inseparable from the compression press. Currently, the most commonly used compression presses in my country are hydraulic presses, with tonnage ranging from several tons to several thousand tons. Generally, compression presses are mainly classified into two types according to their structure: one is the three-beam, four-column hydraulic press, which is a unidirectional pressing type, further divided into upward-moving types (see...). Figure 5 ) and shift down (see Figure 6 There are two types. It consists of two main parts: the machine body and the hydraulic system. The machine body of the hydraulic press mainly consists of the upper crossbeam, the machine column, the movable crossbeam, the lower crossbeam, and the press plunger. The other type is the five-beam, four-column hydraulic press (see...). Figure 7 (This refers to a two-way pressing hydraulic press, which is a double-moving type with both upper and lower movement.)

[0007] Typically, unidirectional presses are used for tamping explosives, where granular explosives are loaded into the chamber or mold, and pressure is transmitted through a punch. Due to various resistances, this tamping process results in a gradient between tamping pressure and density, leading to uneven density in the tamped explosive pellets. This unevenness becomes more pronounced with larger pellets, especially those with a large aspect ratio (≥2), posing a significant challenge for precision loading and high-performance detonation. The root cause of this uneven density distribution is the varying pressure at different locations during granular compression. The tamping pressure is highest near the punch and decreases with distance. Therefore, in unidirectional tamping, the density of the pellet near the base is lower than that near the punch. Using a bidirectional press, however, increases production costs. During tamping, the compression deformation of loosely packed explosive particles is achieved through mutual sliding, continuously reducing the volume of voids between them. When explosives are loosely packed and pressurized to several thousand atmospheres, the porosity decreases by about 10 times and the density increases by about 100%. Because tiny pores (air pockets) remain between explosive particles in a compressed charge, the compressed charge density can usually only reach 95% of the theoretical density of the explosive.

[0008] Therefore, how to achieve bidirectional compression of large aspect ratio (≥2) propellant columns on a conventional unidirectional upward-moving press, reduce production costs, improve production efficiency, increase the compression density and density distribution uniformity of the propellant columns, ensure the strength of the compressed propellant columns, and avoid defects such as cracks and collapse of the propellant columns has become an urgent technological problem to be solved. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of the current conventional unidirectional press process for pressing explosives with large aspect ratios, and to provide a bidirectional combined multi-mold precision pressing process that has the advantages of high explosive strength, good density distribution uniformity, good economy, and high production efficiency, while avoiding defects such as cracks and collapses during the explosive forming process, and producing high-quality explosives.

[0010] To achieve the above design objectives, the technical solution adopted by this invention is: a bidirectional combined multi-mode precision drug pressing process method, comprising the following steps: Step (1): Explosive preparation, optimize the explosive formula, improve the physicochemical properties of the explosive particles, use reasonable particle size distribution and explosive crystal spheroidization technology to reduce the porosity between explosive particles, and then use high-density spheroidized black oxojin and octogen high-energy explosive particles with smooth surfaces and shapes as close to circles as possible to reduce crystal defects and improve crystal density and compressibility. Step (2): Weigh the explosives and add functional additives to the mixed explosives to improve flowability, uniformity and chemical stability, increase the mechanical strength of the explosive charge, increase the plasticity of the explosive charge, reduce the elastic modulus and prevent cracks. Step (3): Mold preparation. When the ratio of the height to the diameter of the pressed drug column is greater than 2, a floating mold sleeve and two punches are used to achieve bidirectional drug pressing on a normal unidirectional press, thereby reducing the axial density difference of the drug column and increasing the strength of the drug column. Step (4): Pour the medicine and fill the punch. The running speed of the press head during the entire stroke is controlled by a program in three gradients. From the initial stage of the press head's running stroke to the middle stage and then to the final stage, the pressing speed is gradually reduced from high speed to low speed according to the three gradients. Step (5): Set the pressing process parameters, appropriately increase the temperature of the explosive during pressing, and according to the different types of explosives being pressed, increase the temperature of the explosive to three different temperature ranges, and keep the pressing system in a constant temperature state; Step (6): Pressing the drug, using the stress release technology of "heating-cooling" temperature cycle impact, first heating the drug column in the mold to a high temperature of 60℃~70℃, holding for 10min, and then cooling to a low temperature of 5℃~15℃, holding for 10min, repeating this cycle twice. Step (7): Demolding. The stress release technology of "pressurization-depressurization" in two pressure cycles is adopted to effectively release the stress inside the propellant and improve the strength of the propellant. After the press head completes one working cycle of "downward pressing-holding pressure-upward return depressurization", the next working cycle is repeated. Step (8): Check the density of the explosive charge. During the pressing process, the explosive in the inner cavity of the mold is evacuated. The vacuum degree reaches below 0.1KPa and is maintained continuously to press the explosive under vacuum. Step (9): Inspect the dimensions of the drug cartridges. This is achieved by integrating multiple sets of molds (≥4 sets) into a single integrated modular mold (see Appendix). Figure 8 This allows a single ordinary press to press multiple drug columns simultaneously, thus multiplying the drug production efficiency. Step (10): Inspect the appearance of the medicine column. During the pressing process, the PLC program is used to automatically control the technical parameters such as the pressure head stroke, pressing pressure, pressing speed, mold temperature, and mold cavity vacuum degree of the press, which can achieve precise pressing and improve the consistency of medicine column quality. Step (11): Industrial CT inspection of the internal quality of the drug column. Place the drug column on the industrial CT inspection table, close the protective door of the industrial CT inspection room, start the equipment, adjust the resolution and image clarity of the CT inspection equipment, and perform DR and cross-sectional inspection on the drug column. The drug column must be free of cracks, bubbles, looseness, impurities and defects. Mark the qualified and unqualified drug columns according to the industrial CT inspection results, and fill in the "Industrial CT Inspection Report". Step (12): Pack the medicine column into a box. Wrap the surface of the medicine column with antistatic packaging paper, write the number on it, and put it into a packaging box lined with antistatic sponge. The medicine column should be fixed firmly in the packaging box and not move around. Finally, put the packing list and certificate of conformity into the box, close the box lid, fasten the buckle and lock it with lead seal, and transport it out of the factory and into the warehouse.

[0011] In step (1), the explosive formulation is optimized to improve the physicochemical properties of the explosive particles. By using reasonable particle size distribution and explosive crystal spheroidization technology, the porosity between explosive particles is reduced, and the compressibility of the explosive is improved. Secondly, high-energy explosive particles such as high-density spheroidized black oxojin and octogen with smooth surfaces and shapes as close to circles as possible are used. This can significantly reduce crystal defects, improve crystal density and compressibility, effectively reduce the porosity between explosive particles, increase the compressible density, and improve the processability of the compressible. According to the different types of explosives being compressed, the explosive temperature is set to three different temperature ranges: 60℃~70℃, 70℃~80℃, or 80℃~90℃.

[0012] In step (2), functional additives are added to the mixed explosive to improve its flowability, uniformity and chemical stability. High-performance additives are used to improve defects such as cracks that may occur in the explosive. Fibrous substances are added to improve the mechanical strength of the explosive charge. Nitrocellulose and thermoplastic polymers are added to increase the plasticity of the explosive charge, reduce the elastic modulus and prevent cracks. Energetic plasticizers are added to prevent the explosive charge from cracking and collapsing over a wide temperature range and to improve its mechanical properties.

[0013] In step (3), in order to press the drug column with a height-to-diameter ratio greater than 2, reduce the axial density difference of the drug column, increase the strength of the drug column, and reduce the production cost, a floating mold sleeve and two upper and lower punches are used to achieve bidirectional drug pressing on a regular unidirectional press. The base of the bidirectional drug pressing mold is designed as a lower punch. When pressing the drug, the upper punch and the lower punch play the same role, applying basically the same pressure to both ends of the drug column. Achieving bidirectional drug pressing on a regular unidirectional press can effectively reduce production costs and improve the economy of drug pressing.

[0014] In step (4), the PLC programmable controller of the press is used to control the running speed of the press head in three stages throughout the entire stroke. The pressing speed of the first stage of the initial stroke is 1 mm / s, the pressing speed of the second stage is reduced to 0.1 mm / s, and the final third stage uses a micro-motion speed of 0.01 mm / s. This allows the explosive particles to slide, deform elastically and brittlely, and reduce the gap between them to improve the pressing density of the explosive column.

[0015] In step (5), the pressing speed of the charge is controlled by a program in three stages according to the type of explosive being pressed. The pressing speed in the first stage is 1 mm / s, the pressing speed in the second stage is reduced to 0.1 mm / s, and the pressing speed in the third stage is 0.01 mm / s. The holding pressure is 150 MPa to 250 MPa, and the holding time is usually 10 min to 20 min. The mold temperature is first heated to 60℃ to 70℃ and held for 10 min, then cooled to 5℃ to 15℃ and held for 10 min. After the mold sleeve is evacuated, the vacuum degree of the mold cavity is ≤0.1 kPa, which can improve the charge density, reduce charge cracks, increase charge temperature, and also help to achieve uniform charge density distribution, eliminate internal stress of the charge, obtain better charge strength, and at the same time, the charge is less prone to cracking.

[0016] In step (6), the stress release technology of "heating-cooling" temperature cycle impact can effectively release the thermal stress inside the drug column and improve the strength of the drug column. First, the drug column in the mold is heated to 60℃~70℃ and kept at that temperature for 10 minutes. Then it is cooled to 10℃~15℃ and kept at that temperature for 10 minutes. Finally, the "heating-cooling" process is repeated once. This cycle is repeated twice to allow the thermal stress of the drug column pressed in the mold to be fully released in advance, so as to avoid cracks and collapse of the drug column due to thermal stress release after demolding, thereby improving the quality and yield of the drug column.

[0017] In step (7), by adopting the stress release technology of "pressurization-depression" two pressure cycles, the stress inside the explosive column can be effectively released, the strength of the explosive column can be improved, and the press head can perform two working cycles: downward pressing - pressure holding - upward return pressure release. This allows the explosive column in the die to go through two pressure working cycles of being pressed (explosive particles are compressed and plastically deformed) - depressurization (explosive column generates a certain degree of rebound and stress release). This allows the explosive particles in the explosive column to be fully squeezed and deformed, reducing the internal stress between them and improving the strength of the explosive column.

[0018] In step (8), by evacuating the explosive in the inner cavity of the mold during the pressing process, the vacuum degree reaches below 0.1 kPa and is maintained continuously, so that the explosive is pressed under vacuum, which can effectively eliminate the small pores (air holes) between the explosive particles and improve the average density and distribution uniformity of the explosive column.

[0019] In step (9), by integrating multiple sets of molds (≥4 sets) into an integrated combination mold, a single ordinary press can simultaneously press multiple drug columns, thereby increasing the drug production efficiency several times.

[0020] The beneficial effects of this invention are as follows: This invention combines multiple sets of compression molds (≥4) into a single integrated mold group on a conventional upward-moving unidirectional hydraulic press. By employing a two-stage telescopic rod and spring-loaded suspension support structure on the press's worktable, the mold sleeve becomes freely floating, enabling bidirectional pressure application of the explosive within the mold sleeve by the upper and lower punches. During the compression process, the explosive powder within the mold sleeve is evacuated, and the explosive inside the mold sleeve is heated with precise temperature control. Simultaneously, a PLC programmable controller precisely controls the pressing speed of the press head across each stroke range of the compression column, thus achieving a precision compression process for the explosive column. This invention's process achieves precise clustering and bidirectional compression of multiple explosive columns on a conventional upward-moving unidirectional press, offering good economic efficiency, wide applicability, and high production efficiency. The prepared explosive columns have advantages such as a large aspect ratio (≥2), high density and uniform distribution (density difference ≤0.5%), high energy, and good quality. Attached Figure Description

[0021] Figure 1 Schematic diagram of a mold for pressing explosive charge; Figure 2 A schematic diagram of a unidirectional compression mold for cylindrical drug cartridges; Figure 3 This is a schematic diagram of a bidirectional compression mold; Figure 4 This is a schematic diagram of a traditional combined module (group module) bidirectional drug delivery cart structure; Figure 5 This is a schematic diagram of the structure of a three-beam four-column hydraulic press (upward-moving unidirectional pharmaceutical press); Figure 6 This is a schematic diagram of the structure of a three-beam four-column hydraulic press (downward-moving unidirectional pharmaceutical press); Figure 7 This is a schematic diagram of the structure of a five-beam, four-column hydraulic press (two-way medicine press); Figure 8 This is a schematic diagram of the structure of a two-way precision drug compression assembly group (in front of the drug compression column); Figure 9 This is a schematic diagram of the structure of a bidirectional precision drug compression assembly group (after drug compression column); Figure 10 This is a schematic diagram of the structure of a two-way precision drug-pressing assembly mold after demolding (after the drug column is formed); Figure 11 This is a schematic diagram of the pressure head stroke during the bidirectional precision compression molding process. Figure 12 This is a schematic diagram showing the stroke and running speed of the bidirectional precision drug-pressing assembly mold head. Detailed Implementation

[0022] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Figure 1-12 The following is a method for precision drug compression using a bidirectional combined multi-mode molding process: Step (1): Explosive preparation, optimize the explosive formula, improve the physical and chemical properties of the raw materials of explosive particles, use reasonable particle size distribution and explosive crystal spheroidization technology to reduce the porosity between explosive particles, and then use high-density spheroidized black oxojin and octogen high-energy explosive particles with smooth surfaces and shapes as close to circles as possible to reduce crystal defects and improve crystal density and compressibility; during operation, transport the qualified explosives from the warehouse to the workshop for packaging and appearance inspection, sieving, and heating. It must not deteriorate or have impurities. Sieving removes impurities in the explosives, such as sand, glass shards, nails and non-metals, and uses a magnet to remove metal impurities to ensure safety during the pressing process. At the same time, sieving the explosives is also to remove the powder of the explosives. Under the same pressure conditions, the smaller the particles, the greater the coefficient of friction, the lower the density of the explosive column, and the greater the density difference. Place the explosives in the oven for heating and heat preservation for later use. Step (2): Weighing the explosives. Functional additives are added to the mixed explosives to improve flowability, uniformity and chemical stability, increase the mechanical strength of the explosive charge, increase the plasticity of the explosive charge, reduce the elastic modulus and prevent cracking. Weighing the explosives: There are two methods: mass method and volume method. The mass method is to weigh the explosive charge according to the mass of the compressed explosive charge. Generally, an electronic scale with an accuracy of 0.1g is selected. The weighing error is generally controlled below 0.5g. For explosive charges with strict quality tolerance requirements, the mass method should be used. The volume method is to control the amount of explosive by using a measuring hopper with a certain volume. Alternatively, the amount of explosive can be directly measured by the pressing mold. At this time, the mold processing dimensions are required to be accurate. The measuring of explosives in the automatic pressing machine adopts this method. When using volumetric automatic metering, the positions of the die and the lower punch are adjusted appropriately based on the measured loose charge density of each batch of explosives before production. The lower punch is fixed to ensure that the volume inside the die remains constant. Volumetric metering requires the explosives to have good flowability and uniform particle size. Since the particle size of each batch of explosives is not exactly the same, the loose charge density is also different. In particular, for passivated aluminum explosives, the loose charge density of each batch of aluminum powder varies greatly (0.3 g / cm3~0.68 g / cm3) and also differs greatly from the loose charge density after mixing with passivated methyl methacrylate. Therefore, during explosive preparation, unheated explosives are added to the preheated explosives to adjust the loose charge density so that it meets the requirements of volumetric metering. Step (3): Mold preparation. When the ratio of the height to the diameter of the pressed drug column is greater than 2, a floating mold sleeve and two punches (upper and lower) are used to achieve bidirectional drug pressing on a regular unidirectional press, reducing the axial density difference of the drug column and increasing the strength of the drug column. During operation, wipe all parts of the bidirectional precision drug pressing combination mold clean, and apply wax evenly to the working surfaces of the combination mold sleeve, lower punch, and upper punch, according to the attached... Figure 8 The requirement is to assemble the bidirectional precision pressing module group on the pressing carriage base plate of the press, without installing the upper punch at this time; Step (4): Pour the explosive and load the punch. The running speed of the press head during the entire stroke is controlled by a program in three gradients. From the initial stage of the press head's running stroke to the middle stage and then to the final stage, the pressing speed is gradually reduced from high speed to low speed according to the three gradients. During operation, the weighed explosive is loaded into the mold sleeve, and then the punch is installed. The assembled bidirectional precision pressing assembly mold and the pressing trolley are sent to the pressing platform along the track. Step (5): Set the pressing process parameters, appropriately increase the temperature of the explosive during pressing, and according to the different types of explosives being pressed, raise the temperature of the explosive to three different temperature ranges, and keep the pressing system in a constant temperature state; during operation, set the pressing process parameters: start the press, set the positioning column height, explosive pressing speed, holding pressure, holding time, mold temperature, mold cavity vacuum degree and pressing method, and set the pressing method to pressurize-release pressure cycle twice: after the press head completes one working cycle of "downward pressing-holding pressure-upward return pressure release", the next working cycle is performed: "downward pressing-holding pressure-upward return pressure release"; Step (6): Pressing the drug, using the stress release technology of "heating-cooling" temperature cycle impact, first heat the drug column in the mold to a high temperature of 60℃~70℃, hold for 10 minutes, then cool to a low temperature of 5℃~15℃, hold for 10 minutes, repeat this cycle twice; during operation, start the press for automated drug pressing operation. The room temperature should generally not be lower than 18℃ during drug pressing. Pressing the drug involves two pressure cycles of pressurization and depressurization: after the press head completes one working cycle of "downward pressing-holding pressure-upward return pressure release", the next working cycle is performed: "downward pressing-holding pressure-upward return pressure release". The pressing process is as follows: after starting the press, first make the press head move towards The downward motion applies pressure to the upper punch and the explosive. The pressure head first presses down on the upper punch as it descends. At this time, the upper punch and the die sleeve are relatively displaced, pressurizing the explosive. As the upper punch continues to descend, the density of the upper part of the explosive increases, and the explosive particles in the upper part are continuously squeezed. The friction between the explosive and the die sleeve wall gradually increases. When the friction between the explosive and the die sleeve is greater than the supporting force of the combined die support spring, the upper punch will drive the die sleeve to move downward at the same time. The die sleeve will then be relatively displaced with the lower punch, causing the lower punch to press the explosive upward. When the friction between the lower part of the explosive and the die sleeve is greater than the friction between the upper part, the upper punch will press the explosive downward again. This process is repeated until all the explosive is pressed, so that the upper punch and the lower punch press the explosive in the die sleeve from the upper and lower directions respectively (see appendix). Figure 9 This allows for bidirectional drug compression on a standard unidirectional press. After the press reaches the drug compression position, it holds the pressure for 10 to 20 minutes. After the drug column compression is completed, the pressure is released, the press head is retracted upwards, and then the next work cycle is repeated: "downward compression - pressure holding - upward return pressure release". Step (7): Demolding. A stress-relieving technique using two pressure cycles of "pressurization-depressurization" is employed to effectively release the internal stress of the propellant grain and improve its strength. After the press head completes one working cycle of "downward pressing-holding pressure-upward return depressurization," the next working cycle is repeated. During operation, the demolding sleeve is placed on the die sleeve, and the press head moves downward, causing the lower punch to push the formed propellant grain and the upper punch upward out of the die sleeve (see Appendix). Figure 10Retract the press head upwards, remove the ejector sleeve, upper punch, and propellant, pull out the pressing trolley, and the pressing process is complete; Step (8): Check the density of the explosive charge. During the pressing process, the explosive in the inner cavity of the mold is evacuated to a vacuum level below 0.1 kPa and the pressure is maintained to press the explosive under vacuum. During operation, for explosive charges and blocks with regular shapes, such as cylindrical explosive charges or square explosive blocks, the volume and density of the explosive charge can be calculated by calculation. Under the condition that the diameter of the explosive charge (ensuring by the mold) remains unchanged, the height and mass of the explosive charge affect the density of the explosive charge. A density table is made with different height and mass values. In production, the corresponding density can be obtained by referring to the table according to the height and mass value of the explosive charge. However, for explosive charges with irregular shapes, such as hemispherical or explosive charges with protrusions, the density detection method is still the water density method. During the test, some explosive charges can be directly immersed in water, such as TNT and passivated RDX. Some explosive charges need to be immersed in a layer of paraffin before they can be immersed in water, such as ammonium nitrate explosive charges. Usually, at least two explosive charges or blocks are sampled from each pressing machine per shift to determine the density. The actual density of the explosive charge is required to reach 99.5% of the theoretical density. Step (9): Inspect the dimensions of the drug column. By integrating multiple sets of molds (≥4 sets) into an integrated combination mold, a single ordinary press can simultaneously press multiple drug columns, thus multiplying the drug pressing production efficiency. During operation, all pressed drug columns and blocks must be 100% inspected according to the requirements of the product drawing. When pressing into a set of combined drug columns, under the condition that the total height of the assembled drug columns meets the requirements, the height tolerance of a single drug column is allowed to exceed the specifications of the drawing (see Appendix). Figure 8 ); Step (10): Inspect the appearance of the propellant. During the pressing process, the PLC program automatically controls the technical parameters of the press head stroke, pressing pressure, pressing speed, mold temperature, and mold cavity vacuum, which can achieve precise pressing and improve the consistency of propellant quality. During operation, the appearance quality of various pressed propellant and blocks must be inspected 100% according to the product drawings and technical specifications. The specific requirements are as follows: a) There must be no oil stains, impurities, or floating powder on the surface of the propellant and blocks; b) The wax layer on the surface of the propellant and blocks should be uniform, complete, and firm, and there must be no impurities, bubbles, or wax accumulation. Wax flow marks that do not affect assembly are allowed on the wax-impregnated surface; c) The paint layer on the surface of the propellant in the fuse transmission and detonating cord should be uniform and complete, and there must be no impurities, bubbles, or deterioration. Step (11): Industrial CT inspection of the internal quality of the drug column. Place the drug column on the industrial CT inspection table, close the protective door of the industrial CT inspection room, start the equipment, adjust the resolution and image clarity of the CT inspection equipment, and perform DR and cross-sectional inspection on the drug column. The drug column must be free of cracks, bubbles, looseness, impurities and defects. Mark the qualified and unqualified drug columns according to the industrial CT inspection results, and fill in the "Industrial CT Inspection Report". Step (12): Pack the medicine column into a box. Wrap the surface of the medicine column with antistatic packaging paper, write the number on it, and put it into a packaging box lined with antistatic sponge. The medicine column should be fixed firmly in the packaging box and not move around. Finally, put the packing list and certificate of conformity into the box, close the box lid, fasten the buckle and lock it with lead seal, and transport it out of the factory and into the warehouse.

[0023] In step (1), the explosive formulation is optimized to improve the physicochemical properties of the explosive particles. By using reasonable particle size distribution and explosive crystal spheroidization technology, the porosity between explosive particles is reduced, and the compressibility of the explosive is improved. Secondly, high-energy explosive particles such as high-density spheroidized black oxojin and octogen with smooth surfaces and shapes as close to circles as possible are used. This can significantly reduce crystal defects, improve crystal density and compressibility, effectively reduce the porosity between explosive particles, increase the compressible density, and improve the processability of the compressible. According to the different types of explosives being compressed, the explosive temperature is set to three different temperature ranges: 60℃~70℃, 70℃~80℃, or 80℃~90℃.

[0024] According to claim 1, the process method for precision compression of a bidirectional combined group mold is characterized in that, in step (2), functional additives are added to the mixed explosive to improve its flowability, uniformity and chemical stability; high-performance additives are used to improve defects such as cracks that may occur in the explosive; fibrous substances are added to improve the mechanical strength of the explosive charge; nitrocellulose and thermoplastic polymers are added to increase the plasticity of the explosive charge, reduce the elastic modulus and prevent cracks; energetic plasticizers are added to prevent the explosive charge from cracking and collapsing within a wide temperature range, and also to improve its mechanical properties.

[0025] According to claim 1, the process method for precision pressing of bidirectional combined mold is characterized in that, in step (3), in order to press a drug column with a height-to-diameter ratio greater than 2, reduce the axial density difference of the drug column, increase the strength of the drug column, and reduce the production cost, a floating mold sleeve and two upper and lower punches are used to realize bidirectional pressing on a common unidirectional press. The base of the bidirectional pressing mold is designed as a lower punch. When pressing the drug, the upper punch and the lower punch play the same role and apply basically the same pressure to both ends of the drug column. The bidirectional pressing can effectively reduce the production cost and improve the economy of pressing the drug by realizing bidirectional pressing on a common unidirectional press.

[0026] According to claim 1, the process method for precision compression of explosives using a bidirectional combined group of modules is characterized in that, in step (4), the PLC programmable controller of the press is used to control the running speed of the press head in three gradients throughout the entire stroke. The initial compression speed of the first stage of the compression stroke is 1 mm / s, the compression speed of the second stage stroke is reduced to 0.1 mm / s, and the final third stage stroke uses a micro-motion speed of 0.01 mm / s for compression. This allows the explosive particles to fully slide, undergo elastic-plastic deformation, and brittle deformation to reduce the gap between them and improve the compression density of the explosive column.

[0027] According to claim 1, a process method for precision compression of explosives using a bidirectional combined mold is characterized in that, in step (5), the compression speed of the explosive is controlled by a three-stage gradient according to the type of explosive being compressed. The compression speed in the first stage is 1 mm / s, the compression speed in the second stage is reduced to 0.1 mm / s, and the compression speed in the third stage is 0.01 mm / s. The holding pressure is 150 MPa to 250 MPa, and the holding time is usually 10 min to 20 min. The mold temperature is first heated to 60°C to 70°C and held for 10 min, then cooled to 5°C to 15°C and held for 10 min. After vacuuming the mold sleeve, the vacuum degree of the mold cavity is ≤0.1 kPa, which can improve the density of the explosive, reduce the cracks in the explosive, increase the explosive temperature, and also help to achieve a uniform distribution of explosive density, eliminate internal stress in the explosive, obtain better explosive strength, and at the same time, the explosive is less prone to cracking.

[0028] In step (6), the stress release technology of "heating-cooling" temperature cycle impact can effectively release the thermal stress inside the drug column and improve the strength of the drug column. First, the drug column in the mold is heated to 60℃~70℃ and kept at that temperature for 10 minutes. Then it is cooled to 10℃~15℃ and kept at that temperature for 10 minutes. Finally, the "heating-cooling" process is repeated once. This cycle is repeated twice to allow the thermal stress of the drug column pressed in the mold to be fully released in advance, so as to avoid cracks and collapse of the drug column due to thermal stress release after demolding, thereby improving the quality and yield of the drug column.

[0029] In step (7), by adopting the stress release technology of "pressurization-depression" two pressure cycles, the stress inside the explosive column can be effectively released, the strength of the explosive column can be improved, and the press head can perform two working cycles: downward pressing - pressure holding - upward return pressure release. This allows the explosive column in the die to go through two pressure working cycles of being pressed (explosive particles are compressed and plastically deformed) - depressurization (explosive column generates a certain degree of rebound and stress release). This allows the explosive particles in the explosive column to be fully squeezed and deformed, reducing the internal stress between them and improving the strength of the explosive column.

[0030] In step (8), by evacuating the explosive in the inner cavity of the mold during the pressing process, the vacuum degree reaches below 0.1 kPa and is maintained continuously, so that the explosive is pressed under vacuum, which can effectively eliminate the small pores (air holes) between the explosive particles and improve the average density and distribution uniformity of the explosive column.

[0031] In step (9), by integrating multiple sets of molds (≥4 sets) into an integrated combination mold, a single ordinary press can simultaneously press multiple drug columns, thereby increasing the drug production efficiency several times.

Claims

1. A two-way combined multi-mode precision drug pressing process, comprising the following steps: Step (1): Explosive preparation, optimize the explosive formula, improve the physical and chemical properties of the explosive particles raw materials, use reasonable particle size distribution and explosive crystal spheroidization technology to reduce the porosity between explosive particles, and then use high-density spheroidized black oxojin and octogen high-energy explosive particles with smooth surface and round shape to reduce crystal defects and improve crystal density and compressibility. Step (2): Weigh the explosives and add functional additives to the mixed explosives to improve flowability, uniformity and chemical stability, increase the mechanical strength of the explosive charge, increase the plasticity of the explosive charge, reduce the elastic modulus and prevent cracks. Step (3): Mold preparation. When the ratio of the height to the diameter of the pressed drug column is greater than 2, a floating mold sleeve and two punches are used to achieve bidirectional drug pressing on a normal unidirectional press, thereby reducing the axial density difference of the drug column and increasing the strength of the drug column. Step (4): Pour the medicine and fill the punch. The running speed of the press head during the entire stroke is controlled by a program in three gradients. From the initial stage of the press head's running stroke to the middle stage and then to the final stage, the pressing speed is gradually reduced from high speed to low speed according to the three gradients. By using the PLC programmable controller of the press, the running speed of the press head during the entire stroke is controlled in three stages. The pressing speed in the first stage of the initial stroke is 1 mm / s, the pressing speed in the second stage is reduced to 0.1 mm / s, and the final third stage uses a micro-motion speed of 0.01 mm / s. This allows the explosive particles to slide, deform elastically and brittlely, and reduce the gaps between them, thereby increasing the pressing density of the explosive charge. Step (5): Set the pressing process parameters, increase the temperature of the explosive during pressing, and according to the different types of explosives being pressed, increase the temperature of the explosives to three different temperature ranges, and keep the pressing system in a constant temperature state; Step (6): Pressing the drug, using the stress release technology of "heating-cooling" temperature cycle impact, first heating the drug column in the mold to a high temperature of 60℃~70℃, holding for 10min, and then cooling to a low temperature of 5℃~15℃, holding for 10min, repeating this cycle twice. Step (7): Demolding. The stress release technology of "pressurization-depressurization" in two pressure cycles is adopted to effectively release the stress inside the propellant and improve the strength of the propellant. After the press head completes one working cycle of "downward pressing-holding pressure-upward return pressure release", the next working cycle is repeated. Step (8): Check the density of the explosive charge. During the pressing process, the explosive in the inner cavity of the mold is evacuated. The vacuum degree reaches below 0.1KPa and is maintained continuously to press the explosive under vacuum. Step (9): Inspect the size of the medicine column. By integrating multiple sets of molds into an integrated combination mold, a single ordinary press can press multiple medicine columns at the same time, thus increasing the efficiency of medicine pressing production by several times. Step (10): Inspect the appearance of the medicine column. During the pressing process, the PLC program automatically controls the pressing head stroke, pressing pressure, pressing speed, mold temperature, and mold cavity vacuum degree of the press, which can achieve precise pressing and improve the consistency of medicine column quality. Step (11): Industrial CT inspection of the internal quality of the drug column. Place the drug column on the industrial CT inspection table, close the protective door of the industrial CT inspection room, start the equipment, adjust the resolution and image clarity of the CT inspection equipment, and perform DR and cross-sectional inspection on the drug column. The drug column must be free of cracks, bubbles, looseness, impurities and defects. Mark the qualified and unqualified drug columns according to the industrial CT inspection results, and fill in the "Industrial CT Inspection Report". Step (12): Pack the medicine column into a box. Wrap the surface of the medicine column with antistatic packaging paper, write the number on it, and put it into a packaging box lined with antistatic sponge. The medicine column should be fixed firmly in the packaging box and not move around. Finally, put the packing list and certificate of conformity into the box, close the box lid, fasten the buckle and lock it with lead seal, and transport it out of the factory and into the warehouse.

2. The bidirectional combined group die precision press process method according to claim 1, characterized in that: In step (1), the explosive formulation is optimized to improve the physicochemical properties of the explosive particles. By using reasonable particle size distribution and explosive crystal spheroidization technology, the porosity between explosive particles is reduced, and the compressibility of the explosive is improved. Secondly, high-density spheroidized black oxojin and octogen high-energy explosive particles with smooth surfaces and round shapes are used, which can significantly reduce crystal defects, improve crystal density and compressibility, effectively reduce the porosity between explosive particles, improve the compressive density, and improve the processability of the compressive. According to the different types of explosives being compressed, the explosive temperature is set to three different temperature ranges: 60℃~70℃, 70℃~80℃, or 80℃~90℃.

3. The bidirectional combined group die precision press process method according to claim 1, characterized in that: In step (2), functional additives are added to the mixed explosive to improve flowability, uniformity and chemical stability; high-performance additives are used to improve cracks and defects in the explosive; fibrous substances are added to improve the mechanical strength of the explosive charge; nitrocellulose and thermoplastic polymers are added to increase the plasticity of the explosive charge, reduce the elastic modulus and prevent cracks; energetic plasticizers are added to prevent cracks and collapse of the explosive charge in a wide temperature range and also to improve its mechanical properties.

4. The bidirectional combined multi-mode precision drug compression process method as described in claim 1, characterized in that: In step (3), in order to press the drug column with a height-to-diameter ratio greater than 2, reduce the axial density difference of the drug column, increase the strength of the drug column, and reduce the production cost, a floating mold sleeve and two upper and lower punches are used to achieve bidirectional drug pressing on a regular unidirectional press. The base of the bidirectional drug pressing mold is designed as a lower punch. When pressing the drug, the upper punch and the lower punch play the same role, applying basically the same pressure to both ends of the drug column. Achieving bidirectional drug pressing on a regular unidirectional press can effectively reduce production costs and improve the economy of drug pressing.

5. The bidirectional combined multi-mode precision drug compression process method as described in claim 1, characterized in that: In step (5), according to the different types of explosives being pressed, the pressing speed of the explosive charge is controlled by the program in three stages. The pressing speed of the first stage is 1 mm / s, the pressing speed of the second stage is reduced to 0.1 mm / s, and the pressing speed of the third stage is 0.01 mm / s. The holding pressure is 150 MPa to 250 MPa, and the holding time is 10 min to 20 min. The mold temperature is first heated to 60℃~70℃ and held for 10 minutes, then cooled to 5℃~15℃ and held for 10 minutes. After vacuuming the mold sleeve, the vacuum degree of the mold cavity is ≤0.1KPa. This can improve the density of the propellant, reduce propellant cracks, increase the propellant temperature, and also help to achieve a uniform distribution of propellant density, eliminate internal stress in the propellant, and obtain better propellant strength. At the same time, the propellant is less prone to cracking.

6. The bidirectional combined group die precision press process method according to claim 1, characterized in that: In step (6), the stress release technology of "heating-cooling" temperature cycle impact can effectively release the thermal stress inside the drug column and improve the strength of the drug column. First, the drug column in the mold is heated to 60℃~70℃ and kept at that temperature for 10 minutes. Then it is cooled to 10℃~15℃ and kept at that temperature for 10 minutes. Finally, the "heating-cooling" process is repeated once. This cycle is repeated twice to allow the thermal stress of the drug column pressed in the mold to be fully released in advance, so as to avoid cracks and collapse of the drug column due to thermal stress release after demolding, thereby improving the quality and yield of the drug column.

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