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Structure and composition of bubble wrap packaging machine (detailed graphic and textual explanation version)
Date: 2025-01-13Read: 3
blister packaging machineIt is composed of a heating section (heating the film in contact with the heating section), a forming section (using compressed air or vacuum forming), a filling section (automatic filling or manual filling), a sealing section, a mechanical drive section, a film cover plate [roll (aluminum foil, paper), film feed], and a body structure.
1Heating section
Use a certain heating device to heat the plastic film to achieve the required thermal softening state for molding processing. According to different heat sources, commonly used heating methods include hot air flow heating and thermal radiation heating. The hot air flow heating system directly sprays high-temperature hot air flow onto the surface of the heated material, which has low heating efficiency and is not uniform enough; Thermal radiation heating is the use of radiant heat generated by a heater to heat materials. Its radiation energy comes from electromagnetic waves in the infrared range of the spectrum. Plastic materials have a strong absorption effect on some far-infrared wavelengths, resulting in high heating efficiency. Therefore, thermoforming packaging machines often use far-infrared heating devices. There are two types of heating methods based on the contact between the heater and the material: direct heating and indirect heating. Direct heating is the process of heating a thin sheet by bringing it into contact with a heater. The heating speed is fast but uneven, and it is only suitable for heating thinner materials; Indirect heating is the use of radiant heat to heat near thin sheets, resulting in thorough and uniform heating, but at a slower rate and suitable for both thick and thin materials.
IIForming part
Forming is an important process in the blister packaging process. There are four methods for bubble forming, namely vacuum negative pressure forming, compressed air positive pressure forming, punch assisted compressed air positive pressure forming, and cold pressure forming.
1Vacuum negative pressure forming, also known as vacuum forming, refers to a method of using vacuum to draw a heated and softened film into the bubble cavity of a forming mold to form a certain geometric shape, thereby completing the formation of a bubble cover. Vacuum forming generally uses roller molds, with suction holes at the bottom of the mold grooves, through which air is quickly drawn out. The molded blister has a small size and simple shape, but due to the use of vacuum forming, the blister is unevenly stretched, and the top and rounded corners of the blister are thin, making the blister prone to collapse.
2Compressed air positive pressure molding, also known as blow molding, refers to the use of compressed air (0.3-0.6MPa) pressure to blow heated and softened plastic into the cavities of the molding mold, forming the desired geometric shape bubble cover. The bottom of the groove of the mold is equipped with exhaust holes. When the plastic film deforms, the air between the film molds is quickly discharged through the exhaust holes. The key to its equipment is that the heating device must be directly facing the position of the mold in order to effectively apply the pressure of compressed air to the softened plastic film caused by heat. The molds for positive pressure molding are mostly made into flat plate shapes, with rows and columns of small matrix grooves as stepping mechanisms on the plate molds. The size specifications of the flat plate can be determined according to the actual requirements of the pharmaceutical factory.
3Punch assisted compressed air positive pressure molding is commonly known as punch blow molding. It refers to using a punch to press the heated and softened film into the concave mold cavity groove. When the punch is fully inserted, compressed air is introduced to make the film tightly adhere to the inner wall of the mold cavity, completing the molding process. It should be noted that the punch size is an important parameter, generally its size should be 60% to 90% of the molding cavity. Appropriate punch shape, size, pushing speed, and distance can obtain bubble caps with uniform wall thickness, firm edges, large size, and complex shape. In addition, due to the large size and unique shape of the bubble formed by it, the forming mechanism is generally flat plate type rather than circular roller type.
4Cold press forming, also known as convex concave die cold stamping forming. When the rigidity of packaging materials is high, such as using metal materials as hard sheets, the convex concave die cold stamping method can be used to close the convex concave die and process the metal film. The air between the convex concave die is discharged through the exhaust hole of the forming concave die.
At present, the commonly used molding methods are vacuum negative pressure molding, compressed air positive pressure molding, and punch assisted compressed air positive pressure molding.
Vacuum negative pressure forming
1. Heating mechanism; 2. PVC hard sheet; 3. Mold; 4. Vacuum tube
Compressed air positive pressure molding
1. PVC hard sheet; 2. Mold; 3. Vacuum tube
Punch assisted compressed air positive pressure forming
1. Punch head; 2. Heating mechanism; 3. PVC hard sheet; 4. Mold; 5. Vacuum tube
IIISealing section
Firstly, cover the aluminum foil film on the molded blister filled with medication, and then seal the hard and soft sheets carrying the medication. The basic principle is to heat the inner surface, then apply pressure to make it in close contact, and then use the adhesive to form a heat sealing action. In addition, to ensure the sealing of the pressed surface, diamond shaped dense dots or linear mesh sealing are generally used.
Roll press heat sealing
Also known as continuous sealing, it refers to a sealing method in which the sealed material is tightly bonded by the pressure between two rotating rollers. The circumferential surface of the sealing roller has a mesh pattern to make it more firmly bonded. Along with the pressure sealing, there is also a heating process. The sealing roller consists of two types of wheels, one is a passive heat sealing roller that rotates without power, and the other is a powered active roller. The driven heat sealing roller and the driving roller roll purely by friction, and can generate a certain swing angle under the control of pneumatic or hydraulic cylinders, thereby coming into contact or disengaging from the driving roller. Because the contact area between the two rollers is very small and belongs to linear contact, the pressure per unit area is extremely high, that is, the pressure is high under the same pressure. Therefore, when two materials enter between the two rollers, compression and traction are carried out simultaneously, and a smaller pressure can achieve a better sealing effect.
Schematic diagram of roller press heat sealing mechanism
1. Aluminum foil; 2. PVC foam sheet; 3. Active roller; 4. Hot press roller
Plate pressure heat seal
By using two plate-shaped heating heat sealing plates and a lower template, they come into contact with the surface of the sealing material that arrives at the sealing station, tightly press them together for sealing, and then quickly leave to complete the process. The finished products of heat sealed packaging with plate molds are smoother than those with roller molds, but due to the larger sealing area and lower unit pressure, the required sealing pressure is higher than that of roller molds. In addition, the process conditions of modern high-speed packaging machines cannot provide a long heat sealing time, but if the heat sealing time is too short, the heat sealing between the adhesive layer and the PVC film will not be sufficient. For this reason, it is generally recommended that the heat sealing time be no less than 1 second. Furthermore, to achieve the desired heat sealing strength, a certain heat sealing pressure must be set. If the pressure is insufficient, not only can the adhesive layer of the product not fully adhere to the PVC film for heat sealing, but it may also leave bubbles between the two, which cannot achieve a good heat sealing effect.
Schematic diagram of plate pressure heat sealing mechanism
1. Upper heat sealing plate; 2. Lower heat sealing plate; 3. Cam mechanism
4Indentation and punching mechanism
Indentation includes batch marking and creasing. The industry standard in our country clearly stipulates that "drug blister packaging machines must have batch marking devices". Batch marking can be done at a separate station or at the same station as heat sealing. For the convenience of splitting when taking multiple doses, the unit board is often stamped with easily breakable marks that can be broken by hand. The punching process is to cut the sealed strip packaging product into the specified size. Whether it is vertical or horizontal cutting, the principle should be to save packaging materials, minimize punching edges or no edge punching, and require the four corners of the finished product to be punched into rounded corners for safe use and convenient packaging. If the residual material at the edges and corners after punching is still in the form of a mesh belt, it can be gathered by the rotation of the waste roller, otherwise it can be cut and processed.
5other institutions
① Aluminum foil printing:It must be carried out on a dedicated aluminum foil printing and coating machine, and the principle is to complete the printing of text or patterns through the concave surface of the printing roller, so it is also called gravure printing. It is the process of processing the printing plate roller into printing plate graphics and text, and the graphic and text parts are corroded into ink holes or pits on the surface of the copper layer of the roller; The non graphic part refers to the rotation of the printing plate roller in the ink tank, filling each ink hole with thin ink. When the roller rotates out of the surface ink tank, the excess ink is scraped off by the scraper installed on the surface of the printing plate roller. The printing plate roller rotates and presses against the aluminum foil, transferring the ink from the ink hole to the surface of the aluminum foil, completing the printing. The main raw materials used for printing are medicinal aluminum foil, ink and solvent materials for aluminum foil, and adhesive materials for aluminum foil coating.
② Cooling and shaping device:In order to flatten the aluminum foil and plastic after heat sealing, a cold pressing device with cooling water circulation is often used to flatten the two.