Introduction to the technology and principle of die structure tablet press

die

The die is a tablet press mold for pressing tablets, and the upper and lower punching working faces form the surface shape of the tablet, and the middle die hole diameter is the diameter of the tablet.

The die is the main working component of the tablet press. Usually, a pair of punches consists of three parts: upper punch, middle die and lower punch. The structure of the upper and lower punch is similar, the diameter of the punch is also equal, and the diameter of the punch of the upper and lower punches is medium and The die holes of the die can be slid freely up and down in the middle die hole, but there is no gap that can leak the powder.

According to the shape of the die structure, it can be divided into a circle and a shape (including a polygon and a curve). The shape of the end face of the punch has a flat shape, a bevel shape, a shallow concave shape, a deep concave shape and a comprehensive shape. The flat shape and the oblique edge punch are used for pressing a flat cylindrical tablet, and the shallow concave shape is used for pressing. A double-convex tablet, a deep concave main chip for compressing coated tablets, which is mainly used for pressing shaped tablets. In order to facilitate the identification and taking of drugs, the name of the drug, the dose, and the vertical and horizontal lines can also be engraved on the end face of the die. For tablets of different doses, a suitable size should be selected.

The working process of the tablet press

The working process of the tablet press can be divided into the following steps:

1. The punch portion of the lower punch (with its working position facing upward) extends from the lower end of the middle die hole into the middle die hole to seal the bottom of the middle die hole;

2. Using a feeder to fill the middle mold hole with the drug;

3. The punching part of the upper punch (the working position is facing downward) falls into the middle die hole from the upper end of the middle die hole, and descends a certain stroke to press the powder into a piece;

4, the upper punch lifts out the hole. The undershoot rises to push the tablet out of the middle die hole to complete a tableting process;

5. Undershoot down to the original position and prepare for the next fill.

Tablet mechanism principle 1. Dosage Control Various tablets have different dosage requirements, and large dose adjustments are achieved by selecting dies of different punch diameters. After the die size is selected, the slight dose adjustment is performed by adjusting the depth of the lower punch into the middle die hole, thereby changing the actual length of the middle die hole after the back cover, to achieve the purpose of adjusting the filling volume of the drug in the die hole. Therefore, there should be a mechanism on the tablet press to adjust the original position of the undershoot in the die hole to meet the dose adjustment requirements.

2. Tablet Thickness and Compaction Control The dosage of the drug is determined according to the prescription and pharmacopoeia and cannot be changed. For the storage, storage and disintegration time limits, there is also a requirement for a certain dose of pressure during tableting, which will also affect the actual thickness and appearance of the tablet. Pressure regulation during tableting is essential. This is achieved by adjusting the amount of downstroke in the die hole. Some tablet presses not only have the upper punching down action during the tableting process, but also have the downward action of the undershooting, and the pressing process is completed by the upper and lower punching relative movements. However, the pressure regulation is mostly to achieve pressure regulation and control by adjusting the mechanism of the upper stroke.

Classification of tablet presses

The tablet press can be divided into a single punch tablet press and a multi-punch rotary tablet press.

The single punching machine is a cam (or eccentric) linkage mechanism (similar to the working principle of the punch), which causes the upper and lower punches to produce relative motion to suppress the tablet. The single punch type does not necessarily have only one pair of die work, but also two or more pairs, but multiple pairs of punches are simultaneously punched, thereby causing strict stability and reliability requirements of the mechanism, and the structure is complicated and not used. Single punching machine is batch production, intermittent feeding, intermittent filming, low production efficiency, suitable for laboratory and large-size tablet production.

The multi-punch rotary tablet press machine has a plurality of pairs of punches arranged on the working turntable in a circumferential shape, and the tail portions of each of the upper and lower punches are controlled by the fixed lifting rails. When the upper and lower punches rotate synchronously with the work turntable, they are controlled by the guide rails to perform axial lifting movements, thereby completing the pressing process. At this time, the process of the tablet press is continuous, continuous feeding and continuous filming. As far as the whole machine is concerned, the force is relatively uniform and stable, and it is widely used in formal production. Multi-punch rotary tablet presses are based on the number of die to prepare the machine model, such as 19 punch, 33 punching machine.

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