Comparison of Tablet Feeding Methods
Comparison of Tablet Feed Methods
The feeding system of the tablet press is generally divided into three types: the shoe-type feeding system of the single punching machine, the monthly grid feeding system of the ordinary medium and low-speed rotary tablet press, and the forced feeding system of the divider. High speed and high speed tablet presses.
1 Structural characteristics of the shoe mending system of single punching machine and comparison of tableting process
The main structure of the shoe feeding system is shown in Figure 1. The feeder is in the shape of a shoe, driven by a cam, and swings left and right on the plane of the mold to complete feeding, scraping and pushing operations.
The working process of the shoe feeding system is shown in Figure 2. The upper punch is lifted, the feeder moves above the die hole, the lower punch is lowered to a suitable depth (so that the weight of the contained granules is exactly equal to the tablet weight), the feeder swings on the die, and the granules fill the die hole; (2) scrape. The feeder is separated from the die hole so that the pellets in the die hole are flush with the upper edge of the die hole. (c) Tablets. Lower the upper punch to compress the granules into tablets; (d) Compression. The upper punch is raised and the lower punch is raised so that it is flush with the edge of the die hole. At this time, the feeder moves to the die hole again, pushes the tablet into the drop receiver, and at the same time the lower punch descends, the die is filled with granules again for the second feed, repeat this operation.
2 Structural characteristics of the moon-shaped grid feeding system of ordinary medium and low-speed rotary tablet presses and comparison of tableting processes
The moon-shaped grid feed system of a common low-speed rotary tablet press is shown in Figure 3. The moon-shaped grid feeder is fixed on the template of the turntable, and the bottom surface of the feeder maintains a certain gap (0.05). ~0.1mm) with the surface of the template. When the rotating mold ring passes under the feeder, the drug particles in the grid will fall into the mold holes, and multiple curved grid plates will cause multiple fillings of the drug. The last grid of the feeder is equipped with a scraper, which is closely attached to the working plane of the turntable, which can rotate the turntable and mold ring, and scrape off excess particles on the surface of the mold ring. , and then punch down again to drop again, so that the powder in the die hole will be impacted after the scraper scrapes the material.
The tabletting process of the moon-shaped grid feeder is shown in Figure 4. (1) Filling. When punching holes under the hopper, the pellets will be filled into the die holes. (2) Scrape. When punching down to the upper plane of the feeding guide rail, the excess particles are scraped off by the scraper; (3) When the lower punch travels to the upper side of the lower pressing wheel and the upper punch travels to the lower side of the upper pressing wheel, the two punches The distance between the heads is minimal, and the granules are compressed into tablets.
(4) Push the film. After tablet pressing, the upper and lower punches rise and fall along the guide rail respectively. When the lower punch reaches the upper side of the exit guide, the tablet is pushed out of the die hole and introduced into the container by the scraper, and so on.
3. Structural characteristics of high-speed tablet press machine and high-speed tablet press system and comparison of tablet pressing process
The forced feeding system is a feeding system widely used in sub-high-speed and high-speed rotary tablet presses in recent years (as shown in Figure 5). The forced feeding system is mainly composed of three parts: hopper, feeding motor and forced feeding machine.
The hopper is mainly used to store materials, and its lower part is connected to the forced feeder.
The feeding motor is the power source of the forced feeder, and the speed is adjusted by frequency conversion;
Forced feeder can be divided into gearbox and feeder. The gearbox transmits the power of the feed motor to the two impellers of the feeder. The two impellers rotate in opposite directions to force the material to fill the die holes. A schematic diagram of a tablet computer is shown in Figure 6.
The tablet pressing process of the forced feeding system is basically the same as that of the crescent-shaped grid feeding system, and it is divided into four steps: filling → leveling → compacting → pushing.
4 Comparison of tablet weight difference among three feeding modes of rotary tablet press
The current feeding method is to use the volume of the material to control the weight of the tablet, g = ρv (where g is the weight of the filling material, ρ is the density of the material, v is the volume of the filling material), now the volume of the filling is fixed of the weight