Rotary tablet press loading device and control method

Abstract

The application discloses a rotary tablet loading device, which comprises a machine body, an upper pressing wheel and a lower pressing wheel, and further comprises an upper die unit and a lower die unit, the upper die unit is arranged above the upper pressing wheel and is used for controlling the floating of the upper pressing wheel in the vertical direction, the upper die unit comprises a loader, a load sensor and an upper connecting rod, the loader is fixedly arranged on the machine body, one end of the load sensor is in transmission connection with the loader, and the other end is in fixed connection with the upper connecting rod, the upper connecting rod is in rotary connection with the upper pressing wheel through an upper bearing arranged on a main shaft of the upper pressing wheel, and the lower die unit is arranged below the lower pressing wheel and is used for adjusting the position of the lower pressing wheel in the vertical direction and fixing the lower pressing wheel. The application monitors the real-time load in the tablet pressing process through the load sensor, adjusts the axial stiffness of the elastic medium through the loader, ensures the constancy of the loading load, ensures the compaction effect of the powder tablet pressing, improves the compactness of the powder tablet pressing, and reduces the rebound after unloading, so that the influence of the unloading rebound on the compaction effect is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of rotary tablet presses, in particular to a rotary tablet pressing loading device and a control method. Background Art

[0002] A rotary tablet press is a device that compresses powder materials into tablets in a stable manner and is widely used in material processing in the pharmaceutical, food, and chemical industries. It features a turntable with multiple upper and lower punches distributed around its circumference. Upper and lower pressing wheels are located above and below the turntable. As the turntable rotates, the powder flows through a feeder into a die. The upper and lower pressing wheels, along with the upper and lower punches, compress the powder into tablets. In the rotary tablet press of the prior art, the positions of the upper and lower pressing wheels are fixed during the powder tableting process. When the punch rotates to the pressing wheel through the turntable and the pressing wheel applies an axial load to the punch, the upper punch moves down and the lower punch moves up. The axial load borne by the powder gradually increases in load. When the punch axis coincides with the center of the pressing wheel, the load reaches a maximum value. Then, as the turntable rotates, the upper punch moves up and the lower punch moves down, and the axial load borne by the powder gradually decreases in load. Due to the fast rotation speed of the turntable, the time for the pressing wheel to apply the axial load to the punch is extremely short, which often results in insufficient density of the powder tableting, and after unloading, the tableting effect is poor due to the rebound of the powder. Summary of the Invention

[0003] The object of the present invention is to provide a rotary tablet loading device and a control method to solve the problem mentioned in the background art that the existing rotary tablet press often causes insufficient density of powder tablets during the tableting process, and the tableting effect is poor due to the rebound effect of powder after unloading.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] The servo motor is fixedly arranged on the machine body, one end of the ball screw is transmission connected with the servo motor, and the other end is fixedly connected with the lower connecting rod, and the lower connecting rod is rotationally connected with the lower pressing wheel through the lower bearing installed on the main shaft of the lower pressing wheel.

[0006] Furthermore, the loader includes a piston rod, a cylinder body and a chassis. The piston rod and the chassis are located in the cylinder body and are slidingly sealed with the cylinder body. An elastic medium is provided in the sealed cavity surrounded by the piston rod, the cylinder body and the chassis. The chassis is fixedly connected to the load sensor. Initially, the chassis is located at the bottom of the cylinder body and fits with the bottom surface of the cylinder body.

[0007] Furthermore, the elastic medium may be gas, liquid or elastic solid.

[0008] Furthermore, the loader is controllably connected to a tablet press control system.

[0009] Furthermore, the load sensor is electrically connected to the tablet press control system.

[0010] Furthermore, the servo motor is electrically connected to a tablet press control system.

[0011] A rotary tablet loading control method comprises the following steps:

[0012] S1. Determine the working position of the lower pressing wheel: The tablet press control system calculates the vertical working distance P between the center of the lower pressing wheel and the horizontal center line of the turntable when in the middle position according to Formula 1;

[0013] Formula 1: p = R + a + e / 2;

[0014] Where R is the radius of the pressing wheel, a is the height of a single punch, and e is the thickness of the tablet;

[0015] S2. Adjust the position of the lower pressing wheel: Use an external measuring instrument to measure the vertical distance between the center of the lower pressing wheel and the horizontal center line of the turntable. If the measured value is not equal to the p value, the tablet press control system drives the servo motor to drive the ball screw to move linearly, thereby driving the lower connecting rod and the lower pressing wheel to move vertically, and adjust the vertical distance between the center of the lower pressing wheel and the horizontal center line of the turntable to make it equal to the p value;

[0016] S3. Determine the initial working position of the upper pressing wheel: The tablet press control system calculates the height h of the lower punch relative to the middle position when entering the position according to Formula 2, and calculates the initial working vertical distance q1 between the center of the upper pressing wheel and the horizontal center line of the turntable according to Formula 4;

[0017] Formula 2:

[0018] Wherein, l is the circumferential spacing between the entry position and the middle position, which is calculated according to Formula 3; β is the angle between the tangent line m and the horizontal plane when the side profile of the lower punch and the lower pressing wheel are tangent in the entry position; b is the distance between the intersection point J1 and the tangent point J2; the intersection point J1 is the intersection point of the bottom surface of the lower punch and the tangent line m; the tangent point J2 is the tangent point of the side profile of the lower punch and the lower pressing wheel; and c is the distance between the center of the bottom surface of the lower punch and the intersection point J1.

[0019] Formula 3:

[0020] Where D is the diameter of the distribution circle of the lower punch on the turntable, and N is the number of groups of lower punches;

[0021] Formula 4: q1 = q0 - 2h;

[0022] Where q0 is the vertical distance between the center of the upper pressure wheel and the horizontal center line of the turntable when in the middle position, q0 = p;

[0023] S4. Adjust the initial working position of the upper pressing wheel: adjust the position of the loader and use the external measuring instrument to make the vertical distance between the center of the upper pressing wheel and the horizontal center line of the turntable equal to the q1 value;

[0024] S5. Preload the elastic medium by pushing the piston rod, with a preload F = KΔx, where K is the elastic medium stiffness and Δx is the amount of compression of the elastic medium;

[0025] S6. Start the rotary tablet press. The turntable drives the upper punch, the middle die, and the lower punch to rotate. At the same time, the tablet press control system controls the stroke of the piston rod according to the stroke-time linear equation so that the compression of the elastic medium is always maintained at the △x value, thereby maintaining the pressure acting on the upper punch and the lower punch at a constant preload F.

[0026] The travel-time linear equation:

[0027] Where S is the piston rod stroke, n is the turntable speed, t is the time, and the entry position is taken as the zero point of time;

[0028] S7. Coordinated control of load error: When the turntable drives the upper punch, middle die and lower punch to rotate, when the ends of the upper punch and lower punch begin to contact the upper pressing wheel and lower pressing wheel respectively, the powder in the middle die is instantly compressed and the thickness is sharply reduced, and the tableting thickness e required by the tableting process is reached in an instant. The upper pressing wheel is lifted and moved upward, and the elastic medium is further compressed to show a new elastic medium pressure F'. The elastic medium pressure F' is sensed by the overload sensor and transmitted to the tablet press control system. The load error ε is calculated according to formula 5 and compared with the set error range ε0. When the load error ε exceeds the set error range ε0 and the elastic medium pressure F'>1.05F, compensation is performed according to a stroke displacement of 0.05F / K, that is, the piston rod 1 moves back 0.05F / K. When the load error ε exceeds the set error range ε0 and the elastic medium pressure F'<0.95F, compensation is performed according to a stroke displacement of 0.05F / K, that is, the piston rod 1 moves forward 0.05F / K.

[0029] Formula 5:

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention adopts a vertically adjustable structure for the upper and lower pressing wheels, realizes the up and down movement of the lower pressing wheel by arranging a servo motor, a ball screw and a lower connecting rod, and adjusts and determines the position of the lower pressing wheel according to the required tablet thickness, and floats the upper pressing wheel by arranging an upper mold unit. Before the pressing work, an elastic medium compression method is adopted to adjust its preload, and the initial working position of the upper pressing wheel is adjusted at the same time. During the working process, as the tablet is formed, the tablet thickness gradually decreases, the upper pressing wheel floats to a certain extent, and the load floats during the contact between the upper punch and the upper pressing wheel. The real-time load during the tableting process is monitored by a load sensor, and the axial stiffness of the elastic medium is adjusted by a loader to ensure the constancy of its loading load, thereby ensuring the compaction effect of the powder tablet, improving the density of the powder tablet and reducing the rebound after unloading, thereby reducing the influence of the unloading rebound on the compaction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of the present invention;

[0033] Figure 2 This is a working state diagram of the present invention;

[0034] Figure 3 This is the contact geometry analysis diagram between the lower punch and the pressing wheel when entering the position;

[0035] Figure 4 is the piston rod travel time curve;

[0036] Figure 5 1 is a piston rod travel time graph of an embodiment;

[0037] Figure 6 It is a pressure-time relationship curve during tablet compression;

[0038] Figure 7 This is a graph showing the relationship between pressure and time during the tableting process of the embodiment;

[0039] In the picture:

[0040] 1-piston rod, 2-cylinder body, 3-chassis, 4-load sensor, 5-upper connecting rod, 6-upper bearing, 7-upper pressure roller, 8-upper punch, 9-middle die, 10-powder, 11-lower punch, 12-lower pressure roller, 13-lower bearing, 14-lower connecting rod, 15-ball screw, 16-servo motor, 17-elastic medium, 18-turntable. DETAILED DESCRIPTION

[0041] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] See also Figure 1-Figure 7 , an embodiment provided by the present invention:

[0043] A rotary tablet loading device comprises a machine body, an upper pressing wheel 7, a lower pressing wheel 12, a turntable 18, an upper die unit and a lower die unit. The upper pressing wheel 7 and the lower pressing wheel 12 have the same diameter. The turntable 18 is arranged on the machine body and is rotatably connected to the machine body. It is driven by a motor to realize circumferential rotation. The turntable 18 is a disc-shaped component. 17 groups of coaxial punch holes evenly distributed on the upper and lower sides are provided, which are respectively used to install an upper punch 8 and a lower punch 11. A groove is provided in the middle of the turntable 18. A middle die 9 corresponding to the upper punch 8 and the lower punch 11 is installed in the groove. The middle die 9 is filled with powder 10. The upper punch 8 and the lower punch 11 can move axially up and down on the turntable 18, and as the turntable 18 rotates, their motion trajectories move up and down in the punch holes of the turntable 18 and the holes of the middle die 9. The upper die unit is arranged above the upper pressing wheel 7 and is used to control the vertical floating of the upper pressing wheel 7 to keep the upper punch 8 , the lower punch 11 maintains a constant pressure to form a sheet during the action time, the upper die unit includes a loader, a load sensor 4 and an upper connecting rod 5, the loader is fixedly arranged on the machine body, and the upper and lower movements of the upper pressure wheel 7 can be achieved by adjusting the upper and lower positions of the loader, one end of the load sensor 4 is connected to the loader by transmission, and the other end is fixedly connected to the upper connecting rod 5 by a thread, the upper connecting rod 5 is rotatably connected to the upper pressure wheel 7 through the upper bearing 6 installed on the main shaft of the upper pressure wheel 7, the lower die unit is arranged below the lower pressure wheel 12, and is used to adjust and fix the position of the lower pressure wheel 12 in the vertical direction, the lower die unit includes a lower connecting rod 14, a ball screw 15 and a servo motor 16, the servo motor 16 is fixedly arranged on the machine body, one end of the ball screw 15 is connected to the servo motor 16 by transmission, and the other end is fixedly connected to the lower connecting rod 14, and the lower connecting rod 14 is rotatably connected to the lower pressure wheel 12 through the lower bearing 13 installed on the main shaft of the lower pressure wheel 12.

[0044] During operation, the upper punch 8 and the lower punch 11 enter the axial space of the upper pressing wheel 7 and the lower pressing wheel 12 driven by the rotation of the turntable 18. A group of upper punches 8 and lower punches 11 are in the entry position from the beginning of contacting the pressing wheel. When the axis of the upper punch 8 and the lower punch 11 coincides with the center line of the upper pressing wheel 7 and the lower pressing wheel 12, it is the middle position. When the upper punch 8 and the lower punch 11 are out of contact with the pressing wheel, it is the rotation-out position. From the entry position to the middle position, and then to the rotation-out position, the upper punch 8 and the lower punch 11 are axially displaced up and down under the action of the upper pressing wheel 7 and the lower pressing wheel 12, contact the powder 10 in the middle die 9 and extrude and form it, completing the tableting of the powder 10.

[0045] Among them, the loader includes a piston rod 1, a cylinder body 2 and a chassis 3. The piston rod 1 and the chassis 3 are located in the cylinder body 2 and are slidingly sealed with the cylinder body 2. An elastic medium 17 is provided in the sealed cavity surrounded by the piston rod 1, the cylinder body 2 and the chassis 3. The elastic medium 17 can be gas, liquid or elastic solid. In this embodiment, the elastic medium 17 is a compression spring. The chassis 3 is fixedly connected to the load sensor 4 by threads. Initially, the chassis 3 is located at the bottom of the cylinder body 2 and fits with the inner bottom surface of the cylinder body 2, bearing the weight of the upper connecting rod 5 and the upper pressure wheel 7.

[0046] The loader is control-connected to the tablet press control system, the load sensor 4 is electrically connected to the tablet press control system, and the servo motor 16 is electrically connected to the tablet press control system.

[0047] A rotary tablet loading control method comprises the following steps:

[0048] S1. Determine the working position of the lower pressing wheel 12: The tablet press control system calculates the vertical working distance P between the center of the lower pressing wheel 12 and the horizontal center line of the turntable 18 when the tablet press is in the middle position according to Formula 1;

[0049] Formula 1: p = R + a + e / 2;

[0050] Where R is the radius of the pressing wheel, which is 63.5 mm, a is the height of a single punch, which is 133 mm, and e is the thickness of the tablet, which is 8 mm. After calculation, p = 200.5 mm;

[0051] S2. Adjust the position of the lower pressing wheel 12: Use an external measuring instrument to measure the vertical distance between the center of the lower pressing wheel 12 and the horizontal center line of the turntable 18. If the measured value is not equal to the p value, the tablet press control system drives the servo motor 16 to push the ball screw 15 to move linearly, thereby pushing the lower connecting rod 14 and the lower pressing wheel 12 to move vertically, and adjust the vertical distance between the center of the lower pressing wheel 12 and the horizontal center line of the turntable 18 to be equal to the p value;

[0052] S3. Determine the initial working position of the upper pressing wheel 7: When the upper punch 8 and the lower punch 11 just come into contact with the upper pressing wheel 7 and the lower pressing wheel 12 at the entry position, the lower punch 11 will drop compared to the middle position. The height of the drop depends on the contact geometry characteristics of the lower punch 11 and the lower pressing wheel 12 and the circumferential spacing l between adjacent positions. The analysis diagram is as follows: Figure 3 As shown, the tablet press control system calculates the height h of the lower punch 11 relative to the middle position when entering the position according to Formula 2, and calculates the initial working vertical distance q1 between the center of the upper pressing wheel 7 and the horizontal center line of the turntable 18 according to Formula 4;

[0053] Formula 2:

[0054] Wherein, l is the circumferential spacing between the entry position and the intermediate position, calculated according to Formula 3, β is the angle between the tangent line m and the horizontal plane when the side profile of the lower punch 11 and the lower pressing wheel 12 are tangent to each other in the entry position state, in this embodiment, β = 24°, b is the distance between the intersection point J1 and the tangent point J2, the intersection point J1 is the intersection point of the bottom surface of the lower punch 11 and the tangent line m, the tangent point J2 is the tangent point of the side profile of the lower punch 11 and the lower pressing wheel 12, in this embodiment, b = 4.11 mm, c is the distance between the center of the bottom surface of the lower punch 11 and the intersection point J1, in this embodiment, c = 6.35 mm, after calculation, h = 7 mm;

[0055] Formula 3:

[0056] Where, D is the diameter of the distribution circle of the lower punch 11 on the turntable 18, which is 195 mm, and N is the number of groups of the lower punch 11, which is 17 groups. The calculated l = 36 mm;

[0057] In order to achieve the goal of instantly pressing the powder 10 in the middle die 9 into the desired tablet thickness e value when the upper punch 8 and the lower punch 11 initially come into contact with the upper pressing wheel 7 and the lower pressing wheel 12 at the entry position, the position of the upper pressing wheel 7 is lowered without changing the center position of the lower pressing wheel 12, and the distance between its center and the horizontal center line of the turntable 18 is adjusted. The downward adjustment distance is equal to 2h = 14mm;

[0058] Formula 4: q1 = q0 - 2h;

[0059] Wherein, q0 is the vertical distance between the center of the upper pressing wheel 7 and the horizontal center line of the turntable 18 when in the middle position, q0 = p = 200.5 mm, and q1 = 186.5 mm is calculated;

[0060] S4. Adjust the initial working position of the upper pressing wheel 7: adjust the position of the loader and cooperate with the external measuring instrument to make the vertical distance between the center of the upper pressing wheel 7 and the horizontal center line of the turntable 18 equal to the q1 value;

[0061] At this point, the setting and fixing of the positions of the upper pressing wheel 7 and the lower pressing wheel 12 are completed. In the actual working process, the lower pressing wheel 12 is a fixed pressing wheel, and the upper pressing wheel 7 is a floating pressing wheel. The center of the circle floats in the vertical direction. In the three states of entry position, middle position, and rotation out position, the distance between it and the horizontal center line of the turntable 18 gradually changes from q1 to q0 and then to q1, thereby realizing the powder pressing of equal thickness on the powder 10 in the middle mold 9.

[0062] S5. Preload the elastic medium 17 by pushing the piston rod 1. The preload force F = KΔx = 80 kN, where K is the stiffness of the elastic medium 17, which is 10 kN / mm, and Δx is the compression of the elastic medium 17, which is 8 mm. At this time, the elastic medium 17 is in a certain compression state, and its reaction force acts on the piston rod 1 and the chassis 3 respectively. The chassis 3 is in a force equilibrium state, and it bears the axial pressure given by the elastic medium 17 and the support force given by the bottom of the cylinder body 2 respectively. At this time, the piston rod 1, cylinder body 2, chassis 3, load sensor 4, upper connecting rod 5, upper bearing 6, and upper pressure wheel 7 form a preloaded whole.

[0063] S6. Start the rotary tablet press. The turntable 18 drives the upper punch 8, the middle die 9, and the lower punch 11 to rotate. At the same time, the tablet press control system controls the stroke of the piston rod 1 according to the stroke-time linear equation, so that the compression of the elastic medium 17 is always maintained at △x = 8 mm, thereby maintaining the pressure acting on the upper punch 8 and the lower punch 11 at a constant preload F = 80 kN.

[0064] The travel-time linear equation:

[0065] Where, S is the stroke of the piston rod 1, n is the rotation speed of the turntable 18, which is 60 r / min, t is the time, and the entry position is taken as the zero point of time;

[0066] The piston rod 1 travel time curve is as follows Figure 4 As shown;

[0067] Substituting the specific values ​​of each parameter into the stroke-time linear equation of this embodiment is obtained:

[0068]

[0069] The stroke time curve of the piston rod 1 in this embodiment is as follows Figure 5 As shown;

[0070] S7. Coordinated control of load error: When the turntable 18 drives the upper punch 8, the middle die 9 and the lower punch 11 to rotate, the ends of the upper punch 8 and the lower punch 11 begin to contact the upper pressing wheel 7 and the lower pressing wheel 12 respectively, and are located in the entry position. At this moment, the powder 10 in the middle die 9 is instantly compressed, and the thickness is sharply reduced, and the tableting thickness e required by the tableting process is reached in an instant. At this time, the upper pressing wheel 7 and the lower pressing wheel 12 are both subjected to the reaction pressure of the powder, and the upper pressing wheel 7 begins to rise. During the process, the load sensor 4 will sense the pressure, and the stress state of the chassis 3 will change. The stress state is transformed from the original equilibrium state formed by the elastic medium 17 and the bottom of the cylinder 2 to the equilibrium state formed by the elastic medium 17, the bottom of the cylinder 2, and the load sensor 4. The force acting between the chassis 3 and the bottom of the cylinder 2 will be partially transferred to the load sensor 4. As the upper pressure wheel 7 is lifted, the load on the load sensor 4 reaches a large value at the moment, which is equal to the pre-pressure F of the elastic medium 17. At this time, the bottom of the cylinder 2 The reaction force on the chassis 3 becomes 0 and is all transferred to the load sensor 4, the upper connecting rod 5, the upper pressure wheel 7 and the upper punch 8. As the turntable 18 continues to drive the upper punch 8, the middle die 9 and the lower punch 11 to rotate, the upper pressure wheel 7 is lifted and moved upward. At this time, when the piston rod 1 does not move in the axial stroke, the elastic medium 17 will be further compressed, which shows a new force F'. The elastic medium pressure F' is sensed by the overload sensor 4 and transmitted to the tablet press control system. The load error is calculated according to Formula 5. The difference ε is compared with the set error range ε0, and the set error range ε0 is ±5%. When the load error ε exceeds the set error range ε0 and the elastic medium pressure F'>1.05F, compensation is performed according to the stroke displacement of 0.05F / K, that is, the piston rod 1 moves back 0.05F / K. When the load error ε exceeds the set error range ε0 and the elastic medium pressure F'<0.95F, compensation is performed according to the stroke displacement of 0.05F / K, that is, the piston rod 1 moves forward 0.05F / K.

[0071] Formula 5:

[0072] At this point, the powder 10 is formed into a sheet by maintaining a constant pressure during the action time between the upper punch 8 and the lower punch 11. The pressure-time relationship curve is shown in FIG. Figure 6 As shown, the pressure-time relationship curve of this embodiment is as follows Figure 7 As shown in the figure, it can be seen that from the entry position to the rotation out position, the pressure is always maintained at 80kN, thereby ensuring the compaction effect of the powder tablet, improving the density of the powder tablet and reducing the rebound after unloading, reducing the influence of unloading rebound on the compaction effect.

[0073] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A rotary tablet loading control method, characterized in that: The invention is applied to a rotary tablet loading device, which comprises a machine body, an upper pressing wheel (7), a lower pressing wheel (12), an upper die unit and a lower die unit. The upper die unit is arranged above the upper pressing wheel (7) and is used to control the floating of the upper pressing wheel (7) in the vertical direction. The upper die unit comprises a loader, a load sensor (4) and an upper connecting rod (5). The loader is fixedly arranged on the machine body. One end of the load sensor (4) is connected to the loader by transmission, and the other end is fixedly connected to the upper connecting rod (5). The upper connecting rod (5) is connected to the upper pressing wheel (7) through an upper bearing (6) installed on the main shaft of the upper pressing wheel (7). The lower die unit is arranged below the lower pressing wheel (12) and is used to adjust and fix the position of the lower pressing wheel (12) in the vertical direction. The lower die unit includes a lower connecting rod (14), a ball screw (15) and a servo motor (16). The servo motor (16) is fixedly arranged on the machine body. One end of the ball screw (15) is connected to the servo motor (16) in a transmission manner, and the other end is fixedly connected to the lower connecting rod (14). The lower connecting rod (14) is connected to the lower pressing wheel (12) in a rotational manner through a lower bearing (13) installed on the main shaft of the lower pressing wheel (12). The loader comprises a piston rod (1), a cylinder (2) and a chassis (3); the piston rod (1) and the chassis (3) are located in the cylinder (2) and are connected to the cylinder (2) in a sliding and sealing manner; an elastic medium (17) is provided in the sealed cavity surrounded by the piston rod (1), the cylinder (2) and the chassis (3); the chassis (3) is fixedly connected to the load sensor (4); initially, the chassis (3) is located at the bottom of the cylinder (2) and is in contact with the inner bottom surface of the cylinder (2); The loader is controlled and connected to the tablet press control system; The rotary tablet loading control method specifically includes the following steps: S1. Determine the working position of the lower pressing wheel (12): The tablet press control system calculates the vertical working distance P between the center of the lower pressing wheel (12) and the horizontal center line of the turntable (18) at the middle position according to Formula 1; Formula 1: p=R+a+e / 2; Where R is the radius of the pressing wheel, a is the height of a single punch, and e is the thickness of the tablet; S2. Adjust the position of the lower pressing wheel (12): Use an external measuring instrument to measure the vertical distance between the center of the lower pressing wheel (12) and the horizontal center line of the turntable (18). If the measured value is not equal to the p value, the tablet press control system drives the servo motor (16) to push the ball screw (15) to move linearly, thereby pushing the lower connecting rod (14) and the lower pressing wheel (12) to move in the vertical direction, and adjust the vertical distance between the center of the lower pressing wheel (12) and the horizontal center line of the turntable (18) to make it equal to the p value; S3. Determine the initial working position of the upper pressing wheel (7): The tablet press control system calculates the height h of the lower punch (11) relative to the middle position when entering the position according to Formula 2, and calculates the initial working vertical distance q1 between the center of the upper pressing wheel (7) and the horizontal center line of the turntable (18) according to Formula 4; Formula 2: ; Wherein, l is the circumferential spacing between the entry position and the middle position, which is calculated according to Formula 3, β is the angle between the tangent line m and the horizontal plane when the side profile of the lower punch (11) and the lower pressing wheel (12) are tangent to each other in the entry position state, b is the distance between the intersection point J1 and the tangent point J2, the intersection point J1 is the intersection point of the bottom surface of the lower punch (11) and the tangent line m, the tangent point J2 is the tangent point of the side profile of the lower punch (11) and the lower pressing wheel (12), and c is the distance between the center of the bottom surface of the lower punch (11) and the intersection point J1; Formula 3: ; Wherein, D is the distribution circle diameter of the lower punch (11) on the turntable (18), and N is the number of groups of the lower punch (11); Formula 4: q1=q0-2h; Where q0 is the vertical distance between the center of the upper pressure wheel (7) and the horizontal center line of the turntable (18) when in the middle position, q0=p; S4. Adjust the initial working position of the upper pressing wheel (7): adjust the position of the loader and cooperate with the external measuring instrument to make the vertical distance between the center of the upper pressing wheel (7) and the horizontal center line of the turntable (18) equal to the q1 value; S5. Preload the elastic medium (17) by pushing the piston rod (1), with a preload force F = KΔx, where K is the stiffness of the elastic medium (17) and Δx is the compression amount of the elastic medium (17); S6. Start the rotary tablet press, the turntable (18) drives the upper punch (8), the middle die (9), and the lower punch (11) to rotate, and at the same time, the tablet press control system controls the stroke of the piston rod (1) according to the stroke-time linear equation, so that the compression amount of the elastic medium (17) is always maintained at the △x value, thereby keeping the pressure acting on the upper punch (8) and the lower punch (11) at a constant preload F; The travel-time linear equation: ; Where S is the stroke of the piston rod (1), n ​​is the rotation speed of the turntable (18), t is the time, and the entry position is taken as the zero point of time; S7. Coordinated control of load error: When the turntable (18) drives the upper punch (8), the middle die (9), and the lower punch (11) to rotate, when the ends of the upper punch (8) and the lower punch (11) begin to contact the upper pressing wheel (7) and the lower pressing wheel (12), respectively, the powder (10) in the middle die (9) is compressed instantly, and the thickness is drastically reduced, and the tableting thickness e required by the tableting process is reached in an instant. The upper pressing wheel (7) is lifted and moved upward, and the elastic medium (17) is further compressed to show a new elastic medium pressure F'. The elastic medium pressure F' is reduced by the load. The sensor (4) senses and transmits it to the tablet press control system, calculates the load error ε according to formula 5 and compares it with the set error range ε0. When the load error ε exceeds the set error range ε0 and the elastic medium pressure F'>1.05F, compensation is performed according to the stroke displacement of 0.05F / K, that is, the piston rod 1 moves back 0.05F / K. When the load error ε exceeds the set error range ε0 and the elastic medium pressure F'<0.95F, compensation is performed according to the stroke displacement of 0.05F / K, that is, the piston rod 1 moves forward 0.05F / K. Formula 5: .

2. A rotary tabletting loading control method according to claim 1, characterized in that: The elastic medium (17) can be gas, liquid or elastic solid.

3. A rotary tabletting loading control method according to claim 1, characterized in that: The load sensor (4) is electrically connected to the tablet press control system.

4. A rotary tabletting loading control method according to claim 1, characterized in that: The servo motor (16) is electrically connected to the tablet press control system.

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