Technological process of blister packing machine
Because the plastic film is mostly thermoplastic, it is heated and softened on the molding die. It is molded into a concave bubble with the shape and size similar to the shape of the drug to be loaded by vacuum or positive pressure, and then the single or double drug is placed in the concave bubble. After covering with aluminum foil, the plastic film and aluminum foil without the drug (i.e. without the concave bubble) are extruded and bonded into a whole by the pressure roller. According to the commonly used dosage of drugs, the process of aluminum-plastic packaging is completed by cutting several parts (mostly rectangular) of drugs into one piece.
In the blister packaging machine, we need to complete the process of film conveying, heating, concave blister forming, feeding, printing, batch number printing, sealing, indentation, punching and so on. In the process, each station is an intermittent process, which is continuous as a whole.
(1) Film transport blister packaging machine is a multi-functional packaging machine, each packaging process is carried out in different stations. A plurality of film conveying mechanisms are arranged on the packaging machine, whose function is to transport the film and make it pass through the above stations to complete the blister packaging process. The conveying mechanism of various types of blister packaging machine in China includes grooved wheel mechanism, cam rocker mechanism, cam indexing mechanism, ratchet mechanism, etc., which can be selected according to the accuracy of conveying position, acceleration curve and adaptability of packaging materials.
(2) Heating will heat the forming film to the temperature that can be used for thermoforming, which is determined according to the selected packaging materials. For rigid PVC, the temperature range of easy molding is 110-130 ℃. In this range, PVC film has enough thermal strength and elongation. The temperature has an effect on the processing effect of thermoforming and the ductility of packaging materials, so the temperature control is required to be quite accurate. However, it should be noted that the temperature referred to here is the actual temperature of PVC film, which is directly measured on the surface of the film with a point thermometer (the temperature of the heating element is much higher than this temperature).
The heating methods of domestic blister packaging machine include radiation heating and conduction heating. Most of the thermoplastic packaging materials absorb the energy emitted by the infrared ray with the wavelength of μ M. Therefore, it is best to use radiation heating method to heat the film.
Conduction heating is called contact heating. The heating method is to clamp the film between the forming die and the heating roller, or between the upper and lower heating plates. This heating method has been successfully applied to the heating of PVC materials.
The heating element uses electric energy as the heat source, because its temperature is easy to control. The heater has metal tubular heater, milky quartz glass tubular heater and ceramic heater. The former is suitable for conduction heating and the latter two are suitable for radiation heating.
(3) Forming is an important process in the whole packaging process. There are four methods of blister forming.
① Suction molding (negative pressure molding). The heated and softened film is sucked into the blister socket of the formed pancreas to form a certain geometry shape by vacuum pumping, so as to complete the blister forming. Generally, roller mold is used for blister forming, with small size, simple shape, uneven stretching and thin top.
② Blow molding (positive pressure molding). The heated and softened film is blown into the blister cavity of the molding die by compressed air to form the required geometry blister. The formed blister has uniform wall thickness, wide shape and large size. Blow molding is mostly used in plate mold.
③ Punch assisted blow molding. With the help of a punch, the heated and softened film is pressed into the die cavity. When the punch is fully pressed in, compressed air is introduced to make the film close to the inner wall of the die cavity, and the forming process is completed. The punch size is about 60% - 90% of the forming cavity. By reasonably designing the shape and size of the punch, the speed and distance of the punch, the bubble cover with uniform wall thickness, wide edge angle, large size and complex shape can be obtained. Punch assisted molding is mostly used in flat blister packaging machine.
④ Punch and die cold stamping. When the rigid packaging material is used, the hot forming method is obviously not applicable, but the cold stamping method of convex and concave die is used, that is, the convex and concave die are closed to form the diaphragm, and the air is discharged from the vent hole in the forming die.
(4) Filling the formed plastic groove with medicine can use a variety of feeders, and can simultaneously fill a row of grooves with medicine. Through strict mechanical control, the single grain of the gap can be cut into the plastic groove, or it can be spread evenly at a certain speed, and at the same time, it can be fed into ruoqian row groove. Between the hopper and the rotating partition plate, a scraper or a fixed partition plate is used to limit the groove or hole of the rotating partition plate, and only a single drug is dropped. The rotating speed of the rotating diaphragm should match the moving speed of the plastic film with bubbles, that is to ensure that each row of grooves on the film falls into a single drug. If there are several rows of concave bubbles on the plastic film, sufficient length or number of rotating diaphragms shall be set accordingly. For the horizontal shaft partition on the left side, sometimes there is no soft skin plate, but for the width of plastic film, cofferdams and baffles must be set on both sides to prevent drugs from falling out of the film.
Spring hose is mostly stainless steel filament wound dense hose, which is commonly used in aluminum plastic blister packaging of hard capsule. Compared with the inner diameter of the tube, it is slightly larger than the outer diameter of the capsule, which can ensure that only a single row of capsules can be stored in the tube. Attention should be paid to ensure that the hose does not bend, which can ensure the smooth flow of the cavity in the pipe. Generally, with the aid of the vibration of the whole machine, the hose shakes itself, which can make the cavity stored in the lower outlet. There are many types of circlip mechanisms. Ratchet wheel can be used to turn the circlip on and off intermittently, so as to ensure that only one capsule can be released each time the circlip is turned on and off, or the circlip can be turned on and off by reciprocating movement with clearance.
(5) The manual or photoelectric detection device shall be used to check the filling of drugs in time behind the feeder. If necessary, the excess pills can be manually patched or picked up. It is more commonly used to use rotary soft brush, in the plastic film forward, accompanied by slow push sweep. Because the soft brush works close to the plastic film, the surplus pellets always rush to and fro the filling direction, and because the soft brush pushes the button, the vacant pits will also be filled with the pellets.
(6) For printing the name of traditional Chinese medicine products in aluminum plastic packaging, the manufacturer, taking method, etc., the labels that should be prompted to patients need to be printed on the aluminum foil. The above printing work shall be carried out before the introduction machine of aluminum foil as roll is pressed with the plastic film. The mechanism for lettering aluminum foil on the machine also needs a series of mechanisms such as ink smoothing wheel, steel wheel, lettering plate, etc., which will not be introduced here. The non-toxic ink used in printing should also be easy to dry, so as to ensure clear and durable writing.
(7) The medicine is filled in the heat sealing forming membrane blister, and the covering membrane is covered on it, and then both are sealed. Its basic principle is to heat the inner surface, then pressurize it to make close contact, forming a complete welding platform, all of which are completed in a very short time. There are two types of heat seal: roller type and plate type.
① Roller press type. The material to be sealed is continuously sealed between the two rollers. However, the packing material passes between the two rollers and stays for a very short time under the pressure. In order to obtain qualified heat sealing, the speed of the roller must be very slow or the packing material must be fully preheated before passing the heat sealing roller.
② Plate press type. When the materials to be sealed arrive at the sealing station, they contact the sealing surface through the heated heat sealing plate and the lower template, and press them tightly together for welding, and then leave quickly to complete a packaging process cycle. Plate mold heat sealing packaging products are relatively flat, sealing pressure required.
The surface of the heat sealing plate (roller) is made into point or net like striae by chemical milling or mechanical rolling to improve the sealing strength and the appearance quality of the packaging products. But it is more important to play the role of stretching the heat sealing materials during sealing, so as to eliminate the shrinkage fold. However, care must be taken to prevent the film from being punctured during heat sealing.
China's laws have made more and more strict restrictions on product packaging, and put forward higher requirements for marking and printing on packaging materials. In the industry standard of drug blister packaging machine, it is clearly required that the packaging machine must have a batch number printing device. Generally, the production date and batch number are printed by punch molding. The batch number can be printed in a separate station, or in the same station with heat sealing and indentation.
(8) Indentation a piece of aluminum-plastic packaging medicine may be suitable for taking for many times. For the convenience of use, it is possible to punch a fracture mark on one piece. It is convenient to break the piece into several small pieces by hand. Each small piece is the dosage that can be used for one time.
(9) Blanking is the process of blanking the sealed strip packaging products into the specified size (i.e. the size of a piece). In order to save packaging materials, it is hoped that both sides of both longitudinal and transverse blanking knives are the parts needed for each piece of packaging, and the blanking surplus edge shall be minimized as much as possible, because the blanking surplus edge cannot be reused and can only be discarded. Since the edge of the cut package is sharp, it is often necessary to punch the four corners into rounded corners to prevent personal injury. The remaining edges and corners of the finished products are still banded, and they are closed by using a separate roll bar on the machine.