Annular grain constant-volume two-way pressing mold and grain two-way pressing equipment

Abstract

The invention discloses an annular grain constant-volume two-way pressing mold and grain two-way pressing equipment. The mold comprises a mold base, a mold frame, a mold sleeve, an upper pressing head, a lower pressing head, a mold core, a movable cushion block and a reset mechanism. The die frame is fixed on the die holder; a stepped through hole is formed in the mold frame in the vertical direction, the mold sleeve and the lower pressing head are inserted into the stepped through hole of the mold frame, the lower pressing head is located at the bottom of the stepped through hole and supported through the mold base, and the mold sleeve is clamped to the top of the stepped through hole. The die sleeve, the upper pressing head and the lower pressing head are all cylindrical bodies, the upper pressing head is clamped in the die sleeve, and a main body part of the lower pressing head can extend into an inner hole of the die sleeve; a cushion block mounting through hole is formed in the mold frame in the horizontal direction, the movable cushion block is mounted in the cushion block mounting through hole and used for limiting the lower pressing head in the vertical direction, and a reset mechanism is arranged between the movable cushion block and the mold frame; the die core penetrates through inner holes of the lower pressing head, the die sleeve and the upper pressing head; powder is injected through an inner hole of the die sleeve, and the upper pressing head and the lower pressing head are used for bidirectionally and synchronously pressing the grain.

Description

Technical Field

[0001] The present invention belongs to the technical field of the press forming of annular charges, and particularly relates to an annular charge constant-volume bidirectional pressing die and a charge bidirectional pressing device including the pressing die. Background Art

[0002] In modern ammunition systems, as a core component of the ignition system, the production quality of annular charges plays a decisive role in the performance of ammunition.

[0003] The prior art uses a unidirectional pressing process for the preparation of annular charges, and there are the following problems:

[0004] 1. Uneven pressing density: Traditional annular charges mostly use unidirectional pressing. When applying pressure, the powder particles are unevenly stressed. The powder near the pressure application end is squeezed tightly with a large density; for the powder far from the pressure application end, the extrusion force is consumed through the powder layer and becomes smaller, with a significantly lower density. The uneven density of the charge will affect the overall performance stability, resulting in different mechanical responses during combustion, and reducing the accuracy and power of the ammunition.

[0005] 2. Inconsistent combustion speed: It is difficult for the prior art to ensure a uniform internal structure of the charge, with large differences in density and porosity in each region. After the charge is ignited, the regions with a large density and a small porosity burn slowly; the regions with a small density and a large porosity burn quickly because oxygen is easily introduced. The inconsistent combustion speed makes the combustion of the charge unstable and the thrust fluctuate greatly, affecting the accuracy and stability of the flight trajectory of ammunition such as missiles, and seriously deviating from the target in severe cases.

[0006] 3. Uneven charge strength: In the production of initiators, there are significant drawbacks when traditionally pressing large height-diameter ratio charges unidirectionally from one side. During the unidirectional pressure application process, the pressure is transmitted from one end to the other, and the powder is unevenly stressed. The powder near the pressure application end has a large pressure, with the particles tightly packed and a high charge strength; for the powder at the far end, the pressure is weakened after being consumed through the powder layer, and the particles are loosely combined with a low charge strength. When the charge withstands external impacts or internal combustion stresses, the weak regions are prone to cracking and deformation, affecting the structural integrity and reliability of the charge, and reducing the performance of the initiator under complex working conditions.

[0007] 4. There is a risk of corner chipping in the unloading method: In the current unloading process of initiating explosive device production, the bottom unloading method is generally adopted. The specific operation is that after pressing is completed, the worker manually lifts the mold to retract the cushion block, and presses the upper punch head to make the pressed tablet fall out of the mold. However, this unloading method has significant defects. When the tablet falls, the forces on each part of the tablet are not uniform, especially the edge part is prone to receive a large shear force. Under the action of this non-uniform external force, the corners of the tablet are extremely prone to corner chipping due to stress concentration. Once corner chipping occurs, the tablet becomes a waste product, which not only causes waste of raw materials, increases production costs, but also affects the quality stability of the product due to the mixing of waste products into good products, reduces production efficiency, and hinders the production of initiating explosive devices.

[0008] 5. The production process relies on manual intervention and has low production efficiency: The single-direction pressing function is single, and it can only complete basic pressing and volume setting. The functions of key production links are not integrated in the same mold, resulting in the entire production process relying heavily on manual labor, with obvious disadvantages. When assembling the mold, the operators have different controls over the assembly accuracy, which is likely to cause uneven internal gaps in the mold, affecting the uniformity of the shaped charge column and greatly affecting the overall production efficiency, and cannot meet the requirements of modern ammunition production for high precision, high efficiency, and high quality. Only applying pressure from a single direction causes the density distribution inside the shaped charge column to be non-uniform, and there are significant differences in the mechanical strength of each part. Especially in the preparation of shaped charge columns with a large height-diameter ratio, such problems are particularly prominent, and then it causes unstable combustion rates during the ignition process of the shaped charge column, having an extremely adverse impact on the ignition efficiency.

[0009] 6. The design of the pressing mold is difficult to adapt to two-way pressing: Traditional single-direction pressing molds are mostly of general-purpose structures in design, lacking a precise control mechanism for the size of the shaped charge column. This technology only ensures the final pressing volume by controlling the operating distance of the press, and cannot accurately guarantee the volume of the shaped charge column, resulting in large deviations in the size of the shaped charge column and a high rejection rate. Due to the special structure of the annular shaped charge column, the production process includes multiple complex links such as powder volume setting, two-way pressing, and unloading. These links have different requirements and their functions restrict each other, resulting in great obstacles to the integrated design of the mold. Currently, the mold design is difficult to adapt to two-way pressing, with a single function, and can only complete basic pressing and volume setting. The functions of key production links are not integrated in the same mold. Summary of the Invention

[0010] In order to solve the above problems existing in the prior art, the invention provides an annular shaped charge column volume-setting two-way pressing mold and a shaped charge column two-way pressing device, changing the single-direction pressing to a two-way pressing process. The annular shaped charge column volume-setting two-way pressing mold integrates multiple functions such as synchronous two-way pressing, volume-setting charge loading, and unloading, and can greatly improve problems such as uneven density of the shaped charge column, low production efficiency, and direct contact between people and medicine existing in the current production process.

[0011] The object of the present invention is achieved by the following technical solutions:

[0012] As one aspect of the present invention, there is provided a constant-volume bidirectional pressing die for an annular grain, comprising a die base, a die frame, a die sleeve, an upper punch, a lower punch, a die core, a moving cushion block and a reset mechanism; the die frame is fixed on the die base; a stepped through hole is provided in the vertical direction of the die frame, the die sleeve and the lower punch are respectively inserted into the stepped through hole of the die frame, the lower punch is located at the bottom of the stepped through hole and is supported by the die base, and the die sleeve is clamped at the top of the stepped through hole; the die sleeve, the upper punch and the lower punch are all cylindrical bodies, the upper punch is clamped in the die sleeve, and the main body part of the lower punch can extend into the inner hole of the die sleeve; a cushion block installation through hole is provided in the horizontal direction of the die frame, and the moving cushion block is installed in the cushion block installation through hole for vertically limiting the lower punch, and a reset mechanism is arranged between the moving cushion block and the die frame; the die core penetrates through the inner holes of the lower punch, the die sleeve and the upper punch; the powder is injected through the inner hole of the die sleeve and accumulates on the top of the lower punch, and the bidirectional synchronous pressing of the grain is carried out by the upper punch and the lower punch.

[0013] Further, the die frame is of an overall frame structure, including a die frame body and a positioning block. The stepped through hole is arranged in the vertical direction of the die frame body, and the cushion block installation through hole is arranged in the horizontal direction of the die frame body; the positioning block is fixed at the entrance of the cushion block installation through hole; the reset mechanism is fixed at the entrance of the cushion block installation through hole of the die frame body and is positioned by the positioning block.

[0014] Further, the moving cushion block includes a cushion block body, a chuck is arranged in front of the cushion block body, the inner wall shape of the chuck matches the outer diameter of the main body part of the lower punch, and the chuck is used for clamping the lower punch to limit the up and down position of the lower punch; a chute is arranged on the cushion block body, and the chute is slidably connected with the reset mechanism.

[0015] Further, the reset mechanism includes a spring seat and a spring. The spring seat is slidably connected with the chute of the moving cushion block, and the spring seat is fixed on the die frame. The spring abuts between the spring seat and the cushion block body of the moving cushion block.

[0016] Further, the die core is used for forming the inner hole of the annular grain. The die core is of a cylindrical structure and is installed on the die base through a threaded hole designed at the bottom.

[0017] Further, the structures of the upper punch and the lower punch are the same. The lower punch includes a neck and a flange fixed at the bottom of the neck, and the neck is the main body structure of the lower punch.

[0018] Further, the outer diameter of the neck of the upper punch has a clearance fit with the inner diameter of the die sleeve, and the outer diameter of the neck of the lower punch is the same as the outer diameter of the neck of the upper punch.

[0019] Further, the die holder includes a die holder body, and a hollow portion is provided on the die holder body, and the lower pressing head is driven through the hollow portion.

[0020] Further, positioning columns are fixed on the die holder body, and the die holder is fixed to the die carrier through the positioning columns.

[0021] As a second aspect of the present invention, there is provided a bi-directional pressing device for a grain including the annular grain constant-volume bi-directional pressing die, which further includes a bi-directional press and a cushion cylinder; the bi-directional press includes a lower bed body, guide columns, an upper headstock and a bi-directional synchronous driving device, the guide columns are fixed on the lower bed body, and the upper headstock is fixed on the guide columns; the bi-directional synchronous driving device includes an upper driving device, an upper slider, a lower driving device, and a lower slider, the lower slider is slidably connected to the guide columns, and the lower slider is fixed to the driving end of the lower driving device, the upper slider is slidably connected to the guide columns, and the upper slider is fixed to the driving end of the upper driving device; the upper and lower pressing heads of the annular grain constant-volume bi-directional pressing die are driven by the bi-directional synchronous driving device.

[0022] The present invention has the following beneficial effects:

[0023] 1. Uniform pressing density of the grain: By changing the problem of uneven stress of the powder under traditional unidirectional pressing, the present invention adopts a bi-directional synchronous pressing process, and the upper and lower pressing heads are synchronously driven by a press, so that the upper and lower pressing heads simultaneously apply pressure towards each other, ensuring that the pressure on each part of the grain is consistent, making the powder evenly and tightly packed, eliminating the density difference, improving the performance stability of the grain, ensuring consistent combustion mechanical response, enhancing the anti-impact and anti-combustion stress deformation capabilities of the grain, improving the structural integrity and reliability, meeting the high-performance requirements of complex working conditions, and improving the accuracy and power of ammunition.

[0024] 2. Uniform burning speed of the grain: Optimize the internal structure and production process of the grain, precisely control the density and porosity of each region, and make their distribution uniform. Ensure that the burning speed of each region is the same after the grain is ignited, avoid unstable combustion and thrust fluctuations, ensure the precise and stable flight trajectory of the ammunition, and reduce the risk of deviating from the target.

[0025] 3. Ensure the constant-volume pressing effect of the annular grain: Use the die sleeve and the moving cushion block to provide limits for the upper and lower pressing heads respectively. Before pressing the grain, the cylinder drives the moving cushion block to extend into the die carrier, and the lower pressing head is clamped by the chuck to provide a limit for the lower pressing head, which cooperates with the limit provided by the die sleeve for the upper pressing head to restrict the pressing process from the up and down directions.

[0026] 4. Optimize the unloading method to prevent corner chipping: Abandon the traditional manual tapping and demoulding method. The present invention adopts an upward ejection unloading method. After the grain is pressed and formed, the moving cushion block is retracted and reset through a reset mechanism, and the lower pressing head ejects the grain, realizing the full automation of the pressing process. Through the application of uniform external force, the stress on the tablet during demoulding is uniform, eliminating the corner chipping phenomenon caused by edge stress concentration.

[0027] 5. Greatly improve production efficiency and achieve co-line production of multiple specifications: By using the synchronous pressing method, the synchronous drive device realizes fast and stable two-way pressing, changes the situation of low efficiency in the existing pressing process, shortens the production cycle, reduces costs, and meets the needs of large-scale production. The die sleeve, die core and template adopt a standard mechanical interface design, which can achieve co-line production of multiple specifications. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings to be used in the description of the embodiments of the present invention. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the content of the embodiments of the present invention and these drawings.

[0029] Figure 1 Isometric structural schematic diagram of a ring-shaped charge constant-volume two-way pressing die according to Embodiment 1 of the present invention;

[0030] Figure 2 Exploded structural schematic diagram of a ring-shaped charge constant-volume two-way pressing die according to Embodiment 1 of the present invention;

[0031] Figure 3 Front view cross-sectional structural schematic diagram of a ring-shaped charge constant-volume two-way pressing die according to Embodiment 1 of the present invention;

[0032] Figure 4 Isometric structural schematic diagram of the die holder according to Embodiment 1 of the present invention;

[0033] Figure 5 Right view structural schematic diagram of the die holder according to Embodiment 1 of the present invention;

[0034] Figure 6 Bottom view structural schematic diagram of the die holder according to Embodiment 1 of the present invention;

[0035] Figure 7 Assembly schematic diagram of the moving cushion block and the reset mechanism according to Embodiment 1 of the present invention;

[0036] Figure 8 Top view of the assembly structure of the moving cushion block and the reset mechanism according to Embodiment 1 of the present invention;

[0037] Figure 9 Structural schematic diagram of the spring seat according to Embodiment 1 of the present invention;

[0038] Figure 10 Structural schematic diagram of the moving cushion block according to Embodiment 1 of the present invention;

[0039] Figure 11Top view of the moving cushion block structure described in Embodiment 1 of the present invention;

[0040] Figure 12 Front view of the moving cushion block structure described in Embodiment 1 of the present invention;

[0041] Figure 13 Schematic diagram of the die sleeve structure described in Embodiment 1 of the present invention;

[0042] Figure 14 Schematic diagram of the die core structure described in Embodiment 1 of the present invention;

[0043] Figure 15 Schematic diagram of the lower punch structure described in Embodiment 1 of the present invention;

[0044] Figure 16 Schematic diagram of the die base structure described in Embodiment 1 of the present invention;

[0045] Figure 17(a) is a schematic diagram of the initial state of the two-way pressing die described in Embodiment 1 of the present invention;

[0046] Figure 17(b) is a schematic diagram of the state where the moving cushion block of the two-way pressing die described in Embodiment 1 of the present invention is inserted and limited;

[0047] Figure 17(c) is a schematic diagram of the two-way pressing state of the two-way pressing die described in Embodiment 1 of the present invention;

[0048] Figure 17(d) is a schematic diagram of the reset state of the moving cushion block of the two-way pressing die described in Embodiment 1 of the present invention;

[0049] Figure 18 Schematic diagram of the structure of the two-way pressing equipment for the propellant column described in Embodiment 2 of the present invention;

[0050] In the figure:

[0051] 1 - die base; 2 - die holder; 3 - die sleeve; 4 - upper punch; 5 - lower punch; 6 - die core; 7 - moving cushion block; 8 - reset mechanism; 9 - propellant column;

[0052] 11 - die base body; 12 - positioning column; 13 - hollowed-out part;

[0053] 21 - die holder body; 22 - positioning block; 23 - stepped through hole; 24 - cushion block installation; 25 - die base positioning hole;

[0054] 51 - cylinder body; 52 - flange;

[0055] 71 - cushion block body; 72 - chute; 73 - chuck;

[0056] 81 - spring seat; 82 - spring. Detailed implementation manners

[0057] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the convenience of description, only the parts related to the present invention rather than all the structures are shown in the drawings.

[0058] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected", and "fixed" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] Embodiment 1

[0060] As Figures 1 to 3 shown, this embodiment is a constant-volume bi-directional pressing die for an annular grain, including a die base 1, a die frame 2, a die sleeve 3, an upper punch 4, a lower punch 5, a die core 6, a moving spacer 7, and a reset mechanism 8.

[0061] The die frame 2 is fixed on the die base 1; a stepped through-hole 23 is provided in the vertical direction of the die frame 2, and the die sleeve 3 and the lower punch 5 are respectively inserted into the stepped through-hole of the die frame 2. The lower punch 5 is located at the bottom of the stepped through-hole 23 and is supported by the die base 1, and the die sleeve 3 is clamped at the top of the stepped through-hole; the die sleeve 3, the upper punch 4, and the lower punch 5 are all cylindrical bodies. The upper punch 4 is clamped in the die sleeve 3, and the main body part of the lower punch 5 can extend into the inner hole of the die sleeve 3 and is in clearance fit with the inner hole of the die sleeve; a spacer installation through-hole 24 is provided in the horizontal direction of the die frame 2, and the moving spacer 7 is installed in the spacer installation through-hole 24 for vertically limiting the lower punch 5, and a reset mechanism 8 is provided between the moving spacer 7 and the die frame 2; a hollow part 13 is provided on the die base 1 to drive the lower punch 5 through the hollow part 13; the die core 6 penetrates through the inner holes of the lower punch 5, the die sleeve 3, and the upper punch 4; the powder is injected through the inner hole of the die sleeve 3 and accumulates on the top of the lower punch 5, and the bi-directional synchronous pressing of the grain 9 is carried out by the upper punch 4 and the lower punch 5.

[0062] Furthermore, as Figure 4 、 Figure 5 shown, the die frame 2, as the basic support structure of the entire die, is made of high-strength alloy steel, with excellent rigidity and stability, and can withstand the huge pressure during the pressing process. The die frame 2 is a frame structure as a whole, including a die frame body 21 and a positioning block 22. The stepped through-hole is provided in the vertical direction of the die frame body 21, and the spacer installation through-hole 24 is provided in the horizontal direction of the die frame body 21; the positioning block 22 is fixed at the entrance of the spacer installation through-hole 24; the reset mechanism 8 is threadedly connected to the entrance of the spacer installation through-hole 24 of the die frame body 21 and is positioned by the positioning block 22 for vertically positioning the moving spacer 7.

[0063] Furthermore, as shown in Figure 3 , Figures 7 to 12 , the moving cushion block 7 serves as a support for the lower punch and volume setting in the mold. The moving cushion block 7 is of an integral structure, including a cushion block body 71. A chuck 73 is arranged in front of the cushion block body 71. The inner wall shape of the chuck 73 matches the outer diameter of the main body part of the lower punch 5. The chuck 73 is used to clamp the lower punch 5 to limit the up and down position of the lower punch 5. A chute 72 is provided on the cushion block body 71, and it is slidably connected to the reset mechanism 8 through the chute 72.

[0064] Furthermore, as shown in Figure 3 , Figures 7 to 12 , the reset mechanism 8 includes a spring seat 81 and a spring 82. The spring seat 81 is slidably connected to the chute 72 of the moving cushion block 7, and the spring seat 81 is fixed to the mold base 2 by bolts. The spring 82 abuts between the spring seat 81 and the cushion block body 71 of the moving cushion block 7. The extension and recovery functions of the moving cushion block 7 are realized by the cooperation of the cushion block cylinder and the reset mechanism. The cushion block cylinder drives the moving cushion block 7 to extend into the cushion block installation through hole 24 of the mold base 2 and clamp and limit the lower punch 5. After the pressing is completed, the cushion block cylinder retracts, and the spring of the reset mechanism acts on the moving cushion block 7 to help the cushion block disengage from the lower punch 5 and recover and reset.

[0065] Furthermore, as shown in Figure 13 , the mold sleeve 3 is the external mold for the formation of the propellant grain, which plays a key role in the dimensional accuracy of the outer diameter of the propellant grain. The mold sleeve is of a cylindrical structure, and its inner diameter size is precisely designed according to the outer diameter of the required annular propellant grain, and the tolerance is controlled within a very small range.

[0066] Furthermore, as shown in Figure 14 , the mold core 6 is used to form the inner hole of the annular propellant grain. The mold core is of a cylindrical structure, and its outer diameter size is precisely adapted to the inner hole size of the propellant grain, and it is installed on the mold base 1 through the threaded holes designed at the bottom.

[0067] Furthermore, the upper punch 4 and the lower punch 5 have the same structure, and the sizes can be different. As shown in Figure 15 , the lower punch 5 includes a neck 51 and a flange 52 that fixes the bottom of the neck 51. The neck 51 is the main structure of the lower punch 5. The neck 51 is matched with the inner diameter of the mold sleeve 3 and can extend into the inner hole of the mold sleeve 3. In this embodiment, the outer diameter of the neck of the upper punch 4 has a clearance fit with the inner diameter of the mold sleeve 3, and the outer diameter of the neck of the lower punch 5 is the same as the outer diameter of the neck of the upper punch 4.

[0068] The upper punch is a key component for realizing the pressing of the top of the propellant charge, directly contacting the propellant powder and applying pressure. It is made of high-strength and highly wear-resistant alloy steel material, and through precise forging and machining, its dimensional accuracy and surface quality are ensured. The lower punch is responsible for the pressing of the bottom of the propellant charge, and works together with the upper punch to achieve two-way synchronous pressing.

[0069] Further, as Figure 16 shown, the die holder 1 is responsible for providing support for the entire mold. The die holder 1 includes a die holder body 11 and positioning columns 12 fixed on the die holder body 11. The die holder 1 is fixed to the mold frame 2 through the positioning columns 12; a hollow part 13 is provided on the die holder body 11, and the lower punch 5 can be driven through the hollow part 13.

[0070] The working principle of this embodiment is briefly introduced as follows:

[0071] As shown in Fig. 17(a), the upper punch 4 is lifted, and the propellant powder is poured into the mold from the mold sleeve 3;

[0072] As shown in Fig. 17(b), the moving cushion block extends into the cushion block installation through hole of the mold frame, and the main lower punch is clamped through the moving cushion block to provide a limit for the lower punch;

[0073] As shown in Fig. 17(c), the upper and lower punches are driven synchronously in two directions. While the upper punch 4 descends, the lower punch 5 is lifted, and the propellant powder is squeezed simultaneously from above and below to form the propellant charge;

[0074] As shown in Fig. 17(d), after the propellant charge is formed, the upper punch is lifted, the moving cushion block disengages from the lower punch, and under the action of the reset mechanism, it is recovered and reset, and the lower punch ejects the formed propellant charge from the mold sleeve.

[0075] Embodiment 2

[0076] As Figure 18 shown, this embodiment is a device for two-way pressing of a propellant charge, including a two-way press, a cushion block cylinder, and the annular propellant charge constant-volume two-way pressing mold A described in Embodiment 1.

[0077] The two-way press includes a lower bed B, guide columns C, an upper headstock D, and a two-way synchronous driving device. The guide columns C are fixed on the lower bed B, and the upper headstock D is fixed on the guide columns C; the two-way synchronous driving device includes an upper driving device E, an upper slider F, a lower driving device G, and a lower slider H. The lower slider H is slidably connected to the guide columns C, and the lower slider H is fixed to the driving end of the lower driving device G. The upper slider F is slidably connected to the guide columns C, and the upper slider F is fixed to the driving end of the upper driving device E; the upper and lower punches of the annular propellant charge constant-volume two-way pressing mold A are driven through the two-way synchronous driving device.

[0078] The pressing process flow of the device for two-way pressing of a propellant charge in this embodiment is as follows:

[0079] Before pressing inspection, check and debug the parameters of the two-way press to ensure the normal operation of the press. Check whether components such as cylinders and springs are in normal working condition. If there are any abnormalities, repair or replace them in time.

[0080] S1. Fill the powder into the annular charge constant-volume two-way pressing die according to the charge requirements. The cylinder drives the moving cushion block to extend into the cushion block installation through hole of the die holder, and clamps the main lower punch through the moving cushion block to provide a limit for the lower punch.

[0081] S2. Start the two-way synchronous drive device of the two-way press. The upper punch moves downward driven by the upper slider. At the same time, the lower drive device drives the lower punch to move upward. The upper punch and the lower punch apply pressure to the powder in opposite directions at the same time. During the pressing process, the pressure control system of the two-way press will monitor the pressure applied by the upper punch and the lower punch in real time and automatically adjust according to the preset pressure value to ensure that the powder gradually forms into an annular charge under uniform pressure. During the pressing process, the pressure gradually increases at a certain rate to avoid the impact of pressure mutation on the quality of the charge.

[0082] S3. When the powder is pressed to the predetermined size and density, the two-way press maintains the current pressure value for a period of time for pressure holding operation. The pressure holding time is set according to the properties of the powder and the specifications of the charge, generally ranging from a few seconds to dozens of seconds. During the pressure holding stage, the particles inside the charge are further compacted and the density is more uniform, which helps to improve the quality and stability of the charge.

[0083] S4. After the pressure holding is completed, the upper slider of the press returns, driving the upper punch to move upward. At the same time, the lower punch returns downward.

[0084] S5. The cushion block cylinder is loosened, and the moving cushion block is pulled out and reset by the spring to release the limit on the lower punch. Then, under the pushing action of the lower punch, the charge smoothly exits from the material port of the die sleeve.

[0085] S6. The lower punch returns to its original position to prepare for the next pressing.

[0086] The following are the maintenance precautions for the charge two-way pressing equipment described in this embodiment:

[0087] 1. After each pressing, use a compressed air spray gun to remove the residual powder in the die to ensure that there is no powder in the die sleeve, die core, upper punch, lower punch and all corners. For difficult-to-clean places, assist in cleaning with a soft brush, and then wipe the surface of the die with a clean cloth to remove oil stains and impurities.

[0088] 2. Conduct a comprehensive inspection of the die every week. Check the integrity of the die holder structure, whether the connections of all components are loose, measure the dimensions of the die sleeve and die core, and check the elasticity of the spring. If the dimensional deviation exceeds the range, the spring is deformed or the elasticity weakens, repair or replace it in time.

[0089] 3. Lubricate the moving parts of the mold monthly. Apply high-temperature grease to the guide pillars, guide sleeves, the connection parts between the upper punch and the upper slide block of the press, and the connection parts between the lower punch and the cushion block to ensure smooth operation of the parts and reduce wear. After lubrication, run the mold for a trial operation and check the movement of the parts.

[0090] 4. Regularly replace the vulnerable parts according to the usage frequency and actual wear. When the wear of the mold sleeve and mold core affects the dimensional accuracy and quality of the propellant column, replace them with new ones in time; replace the springs and seals according to the specified service life to ensure the normal operation of the mold.

[0091] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A constant-volume bidirectional pressing die for an annular grain, characterized in that It includes a die base, a die holder, a die sleeve, an upper punch, a lower punch, a die core, a movable spacer block and a reset mechanism; the die holder is fixed on the die base; a stepped through hole is provided in the die holder in the vertical direction, the die sleeve and the lower punch are respectively inserted into the stepped through hole of the die holder, the lower punch is located at the bottom of the stepped through hole and is supported by the die base, and the die sleeve is clamped at the top of the stepped through hole; the die sleeve, the upper punch and the lower punch are all cylindrical bodies, the upper punch is clamped in the die sleeve, and the main body part of the lower punch can extend into the inner hole of the die sleeve; a spacer block installation through hole is provided in the die holder in the horizontal direction, and the movable spacer block is installed in the spacer block installation through hole for vertically limiting the lower punch, and a reset mechanism is arranged between the movable spacer block and the die holder; the die core penetrates through the inner holes of the lower punch, the die sleeve and the upper punch; the powder is injected through the inner hole of the die sleeve and accumulates on the top of the lower punch, and the upper punch and the lower punch are used for two-way synchronous pressing of the medicine column.

2. The constant-volume bidirectional pressing die for an annular grain as claimed in claim 1, wherein The die holder is of a frame structure as a whole, including a die holder body and a positioning block. The stepped through hole is arranged in the die holder body in the vertical direction, and the spacer block installation through hole is arranged in the die holder body in the horizontal direction; the positioning block is fixed at the entrance of the spacer block installation through hole; the reset mechanism is fixed at the entrance of the spacer block installation through hole of the die holder body and is positioned by the positioning block.

3. The constant-volume bidirectional pressing die for an annular grain as described in claim 1, wherein The movable spacer block includes a spacer block body, a chuck is arranged in front of the spacer block body, the inner wall shape of the chuck matches the outer diameter of the main body part of the lower punch, and the chuck is used for clamping the lower punch to limit the up and down position of the lower punch; a sliding groove is provided on the spacer block body, and the sliding groove is slidably connected with the reset mechanism.

4. The constant volume and bidirectional pressing die for an annular grain according to claim 3, characterized in that, The reset mechanism includes a spring seat and a spring. The spring seat is slidably connected with the sliding groove of the movable spacer block, and the spring seat is fixed on the die holder. The spring abuts between the spring seat and the spacer block body of the movable spacer block.

5. A constant-volume bidirectional pressing die for an annular propellant grain, characterized in that, The die core is used for forming the inner hole of the ring-shaped medicine column. The die core is of a cylindrical structure and is installed on the die base through a threaded hole designed at the bottom.

6. The constant-volume bi-directional pressing die for an annular grain as claimed in claim 1, wherein The structures of the upper punch and the lower punch are the same. The lower punch includes a neck and a flange fixed at the bottom of the neck, and the neck is the main body structure of the lower punch.

7. The constant-volume bi-directional pressing die for an annular grain as claimed in claim 6, wherein, The outer diameter of the neck of the upper punch has a clearance fit with the inner diameter of the die sleeve, and the outer diameter of the neck of the lower punch is the same as the outer diameter of the neck of the upper punch.

8. A constant-volume bidirectional pressing die for an annular grain, as described in claim 1, characterized in that The die base includes a die base body, and a hollow part is provided on the die base body, and the lower punch is driven through the hollow part.

9. The constant-volume bi-directional pressing die for an annular grain as claimed in claim 8, wherein, Positioning columns are fixed on the die base body, and the die base is fixed to the die holder through the positioning columns.

10. A double-sided pressing device for charges, comprising a double-sided pressing die for constant-volume of annular charges as described in any one of claims 1-9, characterized in that, It also includes a two-way press and a spacer block cylinder; the two-way press includes a lower bed body, guide columns, an upper headstock and a two-way synchronous driving device. The guide columns are fixed on the lower bed body, and the upper headstock is fixed on the guide columns; the two-way synchronous driving device includes an upper driving device, an upper slider, a lower driving device and a lower slider. The lower slider is slidably connected to the guide columns, and the lower slider is fixed at the driving end of the lower driving device. The upper slider is slidably connected to the guide columns, and the upper slider is fixed at the driving end of the upper driving device; the upper and lower punches of the ring-shaped medicine column constant volume two-way pressing die are driven by the two-way synchronous driving device.

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