Some conceptual problems in the production of glas

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Several conceptual problems in the production of medicinal glass

in the manufacturing process of a set of oral liquid bottles with glass tube fixtures, zp-18 tube and bottle machine directly uses the medicinal glass tubes already drawn by the glass tube drawing factory for production. Operators are generally not familiar with some terms of glass manufacturing and do not understand some basic concepts, so it is necessary to clarify the concept

1. glass properties

the viscosity of glass in the melting process is a function of temperature and belongs to a nonlinear relationship. The change rate of viscosity with temperature is a very important index of glass production, which is often referred to as the friability of glass

glass whose viscosity changes rapidly with temperature is called short glass; Glass whose viscosity changes slowly with temperature is called long glass. If the temperature difference between melting and molding is used to judge the glass's workability, the greater the temperature difference, the longer the glass's workability

the viscosity of glass increases with the decrease of temperature, which is the basis for the molding and setting of glass products. Generally, three hardness test methods, cloth, Rockwell and dimension, are stipulated. The length of the glass material directly determines the design speed of the cavitation bottle production equipment and the production efficiency of bottle making by avoiding the rotor and mold cavity surface. Long glass is suitable for manufacturing complex shaped glass products, while short glass is suitable for forming cylindrical glass products

2. The difference between forming and forming

the so-called forming is the process of the processed form of glass products from amorphous to fixed or semi fixed, that is, the processing of amorphous glass materials into products and the processing of predetermined parisons

the so-called forming is the process that the processed form of glass products changes from set and semi-set to set, that is, the process of processing and forming the preform or semi-finished products that have been set

3. principle of round mouth of medicinal glass tube

the surface tension of glass refers to the work done by increasing a unit surface at constant temperature and constant volume on the phase interface between glass and another item. It indicates that the free energy of the surface has the effect of shrinking the surface of the object to the minimum surface area, that is, the trend of shrinking into a sphere

when drawing medicinal glass tubes, irregular burrs are often formed when both ends of the glass tubes are cut off. At this time, after baking with flame, the glass at the edge of the glass tube becomes molten, and the edge of the glass tube becomes a smooth cylindrical shape under the action of surface tension, which is the principle of round mouth. The glass tube passing through the round mouth can reduce the damage of the glass tube and improve the utilization rate of the material during long-distance transportation. Therefore, the national standard stipulates that the ports of glass tubes used for AC r separator in Europe and America must be rounded

4. Significance of bottle bottom thickness control

the property that glass is not destroyed by violent temperature changes is called thermal stability. Thermal stability of glass; The size of the sample is usually expressed by the maximum temperature difference that the sample can withstand without being damaged

when the controlled oral liquid bottle is sterilized at high temperature, the temperature in the sterilization cabinet is generally above 116 ℃, while the working environment temperature is generally about 30cc. In this way, after the filled oral liquid enters the sterilization cabinet, the bottle generally has to withstand a large high temperature difference. If the temperature difference exceeds the limit temperature difference of the glass, the controlled oral liquid bottle will inevitably crack. Besides the linear expansion coefficient of the glass itself, the occurrence of fracture is also related to glass defects, residual stress, the size of the neck gap space, the uniformity of wall thickness and the thickness of the bottom of the bottle

the most common position of fracture is often at the connection between the bottle bottom and the bottle body, which shows that the whole bottle bottom falls off neatly. The reason for this is that the structure at the connection between the bottle bottom and the bottle body is not very smooth and excessive. The thickness of the connection is thicker than the bottle wall, resulting in a slightly uneven structure, resulting in residual structural stress and greatly reduced strength. In addition, the thermal stability of glass has a certain relationship with the wall thickness of the product and the sharp temperature difference that leads to the bottle cracking. The greater the thickness of the product, the smaller the sharp temperature difference that can be tolerated

in the sudden change of temperature, there are different expansions from the surface to the interior along the thickness of the glass, resulting in stress. When the stress exceeds the ultimate strength of the glass, it will cause cracking. Therefore, it is very critical to reduce the expansion coefficient of glass and the thickness of glass bottle bottom. The thickness of bottle bottom must be controlled in production to reduce the phenomenon of bottle bottom falling during high-temperature sterilization

author/(Liu Chao)

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