Precise press-fitting method for special-shaped thin-wall grain
Through the mold design of vacuum pumping and multiple pressing processes, the problems of uneven density and easy cracking in the mold forming of special-shaped thin-walled medicine columns are solved, and high-density, uniform density and defect-free medicine column molding are achieved, improving molding safety and surface finish.
Patent Information
- Application Number
- CN202411638823.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-01-10
AI Technical Summary
The prior art is difficult to effectively form a special-shaped thin-walled medicine column, resulting in low density, uneven density, large internal defects, easy cracking and poor finish of the processed surface.
Using molds including vacuum plate, shell, upward, downward, prepress pad, downward, mold retraction sleeve, mold retraction column and mold retraction pad, through vacuum pumping and multiple pressing processes, simulate bidirectional press forming Technology to ensure uniform column density and molding quality.
The high density, uniform density, no pores and no edge-collapse molding effect of the special-shaped thin-walled medicine column is achieved, which solves the problems of easy cracking of the medicine column and low molding density, and improves molding safety and surface finish.
Smart Images
Figure CN119285420A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a precision press-fitting die and a molding process method for a special-shaped thin-walled drug column, belonging to the technical field of high-grade drug column press-fitting molding. Background Art
[0002] At present, there are very limited methods for forming some special-shaped thin-walled grains. Most of them use the process of injection molding or first press the blank grain into shape and then machine it.
[0003] However, the disadvantages of the injection-molded grain column are: 1. Low density and uneven density distribution; 2. Large defects in the grain column, such as looseness and shrinkage holes; 3. Easy internal stratification and formation of coarse crystals. The disadvantages of the process method of first pressing and forming the blank grain column and then machining it: 1. Increased process safety risks, resulting in a reduced safety factor; 2. The surface finish of the grain column is low, affecting assembly.
[0004] In conventional press-charge technology, due to the structure of the thin-walled propellant column, it is difficult for gas to be discharged from the mold cavity (such as Figure 1 ), and the flowability of the drug column particles in the cavity is poor (the design concept of ordinary molding is that the powder particles can move freely in the cavity as the pressure increases, but the special-shaped thin-walled drug column is different), resulting in insufficient and uneven flow of the drug column during the molding process, and the emergence of high and low density areas. For example, the drug column shown in the figure, due to the mismatch between the design of the surrounding molding cavity and the design of the middle drug cake molding cavity, the density of the surrounding areas is obviously lower than the density of the middle drug cake, which leads to cracking. Summary of the invention
[0005] In order to solve the above technical problems, the present invention provides a method for precision pressing of shaped thin-walled propellants which is easy to operate and can press-fit into shape without further processing and meets the performance requirements of high density, uniform density, no pores, and edge collapse.
[0006] The technical scheme adopted by the present invention is: a method for precision pressing and charging of special-shaped thin-walled medicine columns, which adopts a mold including a vacuum plate, a shell, an upper punch, a lower punch I, a pre-pressing pad, a lower punch II, a demolding sleeve, a demolding column and a demolding pad; a vacuum cavity is provided at the center of the top surface of the upper punch, a vacuum plate is installed on the top of the vacuum cavity, and the exhaust hole on the vacuum plate is connected to the vacuum cavity; a plurality of through holes are provided at the bottom of the vacuum cavity to connect the gap between the upper punch and the shell; the upper punch is placed at the upper part of the inner hole of the shell, and a sealing ring I is provided between the upper punch and the shell; the lower punch II is a circular tubular structure, a positioning flange is provided on the outer side wall of the bottom of the lower punch II, the upper part of the lower punch II is placed at the lower end of the inner hole of the shell, the lower end face of the pre-pressing pad is placed on the positioning flange, and the lower end face of the shell is supported on the pre-pressing pad; the lower punch I is placed in the center hole of the lower punch II, and a sealing ring II is provided between the lower punch I and the lower punch II; the lower punch I is coaxially supported on the pre-pressing seat; the demolding sleeve is a circular tubular structure, and the demolding sleeve, the demolding column and the demolding pad are used for demolding; The steps include: 1) Align the lower punch I on the pre-pressing seat; place the lower punch II outside the lower punch I; place the pre-pressing pad; and put on the shell; 2) 2) Preheat the explosive and the mold separately, pour 1 / 3 of the preheated explosive into the mold cavity with a charging funnel, load all the explosives into the surrounding cavity, then pour another 1 / 3 of the preheated explosive, flatten it, and finally pour the remaining preheated explosive and flatten it with a flattening tool; 3) Place the upper punch and vacuum plate, push the medicine pressing mold to the center of the hydraulic press workbench, evacuate and close the explosion-proof door; evacuate to -0.09MPa~-0.1MPa; start the press and perform the first pressing at a pressure of 3MPa~5MPa, and maintain the pressure for 10S; 4) Open the explosion-proof door, take out the pre-pressing pad and pre-pressing seat, evacuate and close the explosion-proof door; start the press and perform the second pressing at a pressure of 11MPa~13MPa, and maintain the pressure for 30S; 5) Open the explosion-proof door, rotate the mold body 180°, evacuate and close the explosion-proof door; start the press and perform the third pressing with a pressure of 11MPa~13MPa and a holding time of not less than 5400s; 6) After the pressing is completed, open the explosion-proof door of the medicine pressing room, remove the vacuum plate, turn the mold body upside down 180°, place it on the material withdrawal column, and put the mold withdrawal sleeve on the upper end of the shell. People evacuate and close the explosion-proof door; start the press and withdraw the mold; open the explosion-proof door of the medicine pressing room, pull out the mold, disassemble the mold, and take out the medicine column.
[0007] Furthermore, in step 1), before the lower punch II is placed outside the lower punch I, talcum powder and zinc stearate release agent are applied on the working surfaces of the lower punch I), the lower punch II and the shell, and liquid paraffin is applied on the sealing rings I and II.
[0008] Furthermore, in step 2), the explosive used is poly-8 explosive.
[0009] Furthermore, in step 2), when the explosive and the mold are preheated respectively, the preheating temperature of the explosive is 85°C±5°C; the preheating temperature of the mold is 60°C~75°C.
[0010] Furthermore, the vacuum plate is made of 40Cr steel with a quenching hardness of HRC40.
[0011] Furthermore, the pre-pressing pad, the die-removing sleeve and the die-removing column are made of 45 steel with a quenching hardness of HRC30-35. The hardness of the pre-pressing pad, the die-removing sleeve and the die-removing column is less than the hardness of the shell.
[0012] Furthermore, the upper punch, lower punch I, lower punch II and shell are all made of H13 steel, the quenching hardness of the upper punch, lower punch I and lower punch II reaches above HRC45, and the quenching hardness of the cavity reaches above HRC50.
[0013] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts a one-way machine to simulate the forming technology of a two-way press machine, and performs three vacuum pressing forming, which is convenient to operate and has good safety. In the first pressing, under the condition of vacuuming and a large cavity, the powder particles are formed into a low-density medicine column embryo with uniform density, and then the pre-pressing pad in the mold structure is removed, and the second pressing is performed to simulate the two-way pressing. Under this condition, although the fluidity of the formed medicine particles is very poor, due to the initial formation of the low-density medicine column embryo, during the pressing process, the peripheral and middle medicine cakes move along their respective cavities to increase the density, and the density increases by an equal value. In this way, after the mold is completely closed, the pressure is appropriately maintained, so that the elastic deformation of the medicine column is transformed into plastic deformation through time solidification, and finally the medicine column is removed from the mold to obtain a qualified medicine column with high density, uniform density, no cracking, no pores, and no edge collapse; the problems of easy cracking of special-shaped thin-walled medicine columns, low forming density, over-difficulty in size, and uneven density are solved. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a structural diagram of the mold used in the present invention when charging.
[0015] Figure 2 It is a structural diagram of the mold used in the present invention when the upper punch is withdrawn during mold withdrawal.
[0016] Figure 3 It is a structural diagram of the lower punch I when the mold is withdrawn when the present invention is used. DETAILED DESCRIPTION
[0017] The present invention will be further described below in conjunction with the accompanying drawings.
[0018] like Figure 1-3As shown, the mold used in the present invention includes a vacuum plate 1, a shell 2, an upper punch 3, a lower punch I5, a pre-pressing pad 7, a lower punch II8, a mold withdrawal sleeve 11, a mold withdrawal column 12 and a mold withdrawal pad 13. A vacuum cavity is provided at the center of the top surface of the upper punch 3, and a vacuum plate 1 is installed on the top of the vacuum cavity. The vacuum cavity is connected to the vacuum cavity. The bottom of the vacuum cavity is provided with a plurality of through holes connecting the gap between the upper punch and the shell. The upper punch 3 is placed on the upper part of the inner hole of the shell 2, and a sealing ring I4 is provided between the upper punch 3 and the shell 2. The lower punch II8 is a circular tubular structure, and a positioning flange is provided on the outer side wall of the bottom of the lower punch II8, and the upper part of the lower punch II8 is placed at the lower end of the inner hole of the shell 2. The lower end face of the pre-pressing pad 7 is placed on the positioning flange, and the lower end face of the shell 2 is supported on the pre-pressing pad 7. The lower punch I5 is placed in the center hole of the lower punch II8, and a sealing ring II6 is provided between the lower punch I5 and the lower punch II8; the lower punch I5 is coaxially supported on the pre-pressing seat 9.
[0019] The die-removal sleeve 11, die-removal column 12 and die-removal pad 13 are used for die-removal. The die-removal sleeve 11 is a circular tube structure, and one end of the center hole of the die-removal sleeve 11 is provided with an annular groove. The die-removal column 12 and the die-removal pad 13 are both cylindrical structures. When the die-removal sleeve 11 is used to remove the upper punch 3, the lower end of the shell is clamped with the groove of the die-removal sleeve 11, and the die-removal column 12 is coaxially supported on the top surface of the upper punch 3. When the die-removal sleeve 11 is used to remove the lower punch I, the die-removal pad 13 is coaxially supported on the bottom surface of the lower punch I5, and the die-removal sleeve 11 is supported on the positioning flange of the lower punch II8.
[0020] The vacuum plate 1 is made of 40Cr steel with a quenching hardness of HRC40. The pre-press pad 7, the die-removing sleeve 11 and the die-removing column 12 are made of 45 steel with a quenching hardness of HRC30-35. The hardness of the pre-press pad 7, the die-removing sleeve 11 and the die-removing column 12 is less than the hardness of the shell. The upper punch 3, the lower punch I5, the lower punch II8 and the shell are all made of H13 steel. The quenching hardness of the upper punch 3, the lower punch I5 and the lower punch II8 reaches above HRC45, and the quenching hardness of the shell 2 reaches above HRC50.
[0021] The present invention adopts a four-column three-beam downward pressure type 500T one-way pressing machine to carry out explosive molding and demoulding. The parameters of the four-column three-beam downward pressure type 500T one-way pressing machine are as follows: S1 The maximum working medium pressure is 25MPa; S2 return force 1000KN; S3 slider stroke 900mm; S4 opening height 1500mm; S5 The slider descends rapidly ≥30mm / s; S6 slow descent (steplessly adjustable) 4-8 mm / s; S7 constant speed pressing (steplessly adjustable) 0.5~10mm / s; S8 slow return 2~10mm / s, fast return ≥30mm / s; S9 working table effective dimensions (left and right), (front and back) 1400mm; The height of S10 workbench from the ground is 0~200mm.
[0022] The raw material of the explosive used in the present invention is poly-Ao-8 explosive, which is a strong high-energy composite explosive, but has very low mechanical sensitivity and is relatively stable, and is suitable for press-charge molding.
[0023] The present invention comprises the following steps: 1) Apply talcum powder and zinc stearate mold release agent on the working surfaces of the lower punch I5, the lower punch II6 and the shell 2, and apply liquid paraffin on the sealing ring I4 and the sealing ring II6; Align the lower punch I5 on the pre-pressing seat 9; place the lower punch II8 outside the lower punch I5; place the pre-pressing pad 7; and put on the shell 2.
[0024] 2) Preheat the explosive and the mold separately, the explosive preheating temperature is 85℃±5℃; the mold preheating temperature is 60℃~75℃. The explosive is poly-8 explosive. Use the charging funnel to pour 1 / 3 of the preheated explosive into the mold cavity, and put all the explosives into the surrounding cavity (that is, the annular cavity formed by the part of the lower punch I5 that is higher than the lower punch II8 and the shell 2), and then pour in 1 / 3 of the preheated explosive, flatten it, and finally pour in the remaining preheated explosive, and flatten it with a flattening tool.
[0025] The purpose of three-time charging is to fully ensure that the density of the surrounding cavities after forming is consistent with that of the middle medicine cake after forming; to avoid cracking due to the density of the surrounding areas being lower than the density of the middle medicine cake; to fully ensure the local fluidity of the medicine particles in the special-shaped cavity and prevent other internal defects.
[0026] 3) Place the upper punch 3 and the vacuum plate 1, push the medicine pressing mold to the center of the hydraulic press workbench, evacuate and close the explosion-proof door; evacuate the vacuum to -0.09MPa~-0.1MPa; start the press and perform the first pressing at a pressure of 3MPa~5MPa, and maintain the pressure for 10S.
[0027] 4) Open the explosion-proof door, take out the pre-compression pad 7 and the pre-compression seat 9, evacuate and close the explosion-proof door; start the press and perform the second pressing at a pressure of 11MPa~13MPa for 30S.
[0028] 5) Open the explosion-proof door, rotate the mold 180°, evacuate and close the explosion-proof door; start the press and perform the third pressing at a pressure of 11MPa to 13MPa, with a holding time of not less than 5400s. When pressing the pharmaceutical column, the pressing speed is not more than 2mm / s.
[0029] 6) After the pressing is completed, open the explosion-proof door of the pressing room, remove the vacuum plate, turn the mold body upside down 180°, place it on the material withdrawal column 12, and put the mold withdrawal sleeve 11 on the upper end of the shell 2, as shown in the figure. Figure 2 As shown, people evacuate and close the explosion-proof door; open the press and remove the mold; open the explosion-proof door of the pressing room, pull out the mold, and disassemble the mold, as shown in the figure. Figure 3 When removing the mold, the pressure should not be higher than 3MPa, otherwise the mold removal action will be terminated and continue after eliminating the abnormality.
[0030] In order to emphasize safety, the present invention requires operators to wear anti-static work clothes, coarse sand gloves, and double-post system to assemble molds, pour medicine, and draw pre-press pads on site. The pressing and demolding are all completed in the explosion-proof room, and all personnel are evacuated from the safe area, and the man-machine is isolated. The whole process requires gentle handling, and no ferrous metal auxiliary tools are allowed.
Claims
1. A method for precision pressing and charging of special-shaped thin-walled medicine columns, which adopts a mold including a vacuum plate, a shell, an upper punch, a lower punch I, a pre-pressing pad, a lower punch II, a demolding sleeve, a demolding column and a demolding pad; a vacuum cavity is provided at the center of the top surface of the upper punch, a vacuum plate is installed on the top of the vacuum cavity, and the exhaust hole on the vacuum plate is connected to the vacuum cavity; a plurality of through holes are provided at the bottom of the vacuum cavity to connect the gap between the upper punch and the shell; the upper punch is placed at the upper part of the inner hole of the shell, and a sealing ring I is provided between the upper punch and the shell; the lower punch II is a circular tubular structure, a positioning flange is provided on the outer side wall of the bottom of the lower punch II, the upper part of the lower punch II is placed at the lower end of the inner hole of the shell, the lower end face of the pre-pressing pad is placed on the positioning flange, and the lower end face of the shell is supported on the pre-pressing pad; the lower punch I is placed in the center hole of the lower punch II, and a sealing ring II is provided between the lower punch I and the lower punch II; the lower punch I is coaxially supported on the pre-pressing seat; the demolding sleeve is a circular tubular structure, and the demolding sleeve, the demolding column and the demolding pad are used for demolding; The steps include: 1) Align the lower punch I on the pre-pressing seat; place the lower punch II outside the lower punch I; place the pre-pressing pad; and put on the shell; 2) Preheat the explosive and the mold separately, pour 1 / 3 of the preheated explosive into the mold cavity with a charging funnel, load all the explosives into the surrounding cavity, then pour another 1 / 3 of the preheated explosive, flatten it, and finally pour the remaining preheated explosive and flatten it with a flattening tool; 3) Place the upper punch and vacuum plate, push the medicine pressing mold to the center of the hydraulic press workbench, evacuate and close the explosion-proof door; evacuate to -0.09MPa~-0.1MPa; start the press and perform the first pressing at a pressure of 3MPa~5MPa, and maintain the pressure for 10S; 4) Open the explosion-proof door, take out the pre-pressing pad and pre-pressing seat, evacuate and close the explosion-proof door; start the press and perform the second pressing at a pressure of 11MPa~13MPa, and maintain the pressure for 30S; 5) Open the explosion-proof door, rotate the mold body 180°, evacuate and close the explosion-proof door; start the press and perform the third pressing with a pressure of 11MPa~13MPa and a holding time of not less than 5400s; 6) After the pressing is completed, open the explosion-proof door of the medicine pressing room, remove the vacuum plate, turn the mold body upside down 180°, place it on the material withdrawal column, and put the mold withdrawal sleeve on the upper end of the shell. People evacuate and close the explosion-proof door; start the press and withdraw the mold; open the explosion-proof door of the medicine pressing room, pull out the mold, disassemble the mold, and take out the medicine column.
2. The precision pressing method for special-shaped thin-walled powder columns according to claim 1, in step 1), before the lower punch II is placed outside the lower punch I, talcum powder and zinc stearate release agent are applied on the working surfaces of the lower punch I, the lower punch II and the shell, and liquid paraffin is applied on the sealing rings I and II.
3. According to the precision charge charging method of special-shaped thin-walled charge column as described in claim 1, in step 2), the explosive is poly-Ao-8 explosive.
4. The precision charge packing method of special-shaped thin-walled charge columns according to claim 1, wherein in step 2), when the explosive and the mold are preheated respectively, the preheating temperature of the explosive is 85°C ± 5°C; the preheating temperature of the mold is 60°C to 75°C.
5. The precision pressing and charging method of the special-shaped thin-walled grain according to claim 1 is characterized by: The vacuum plate is made of 40Cr steel with a quenching hardness of HRC40.
6. The precision charging method for special-shaped thin-walled grain according to claim 1 is characterized by: pre-pressing The pad, die ejection sleeve and die ejection column are made of 45 steel with a quenching hardness of HRC30-35. The hardness of the pre-pressing pad, die ejection sleeve and die ejection column is less than the hardness of the shell.
7. The precision pressing and charging method of the special-shaped thin-walled grain according to claim 6 is characterized by: The upper punch, lower punch I, lower punch II and shell are all made of H13 steel. The quenching hardness of the upper punch, lower punch I and lower punch II reaches above HRC45, and the quenching hardness of the cavity reaches above HRC50.