Aug.2023 09
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What is the range of temperature difference of glass by machine-pressing can withstand?
Details
1. Mechanical blow molding of glass cups
(1) blowing - blowing method
This method is mostly used to make small-mouth bottles, and vacuum-assisted forming can also be used in the initial mold of the EF-type row machine.
The so-called blow-blow method is to perform a blow molding in the initial mold to shape the mouth and blow it into a prototype, and then transfer it to the forming mold for the second blow molding.
According to different feeding methods, it can be divided into two types of blow-blow molding: vacuum suction and drip feeding.
(2) Rotation blowing method
Refers to the non-stop rotation when blowing the bubble.
In the rotary blowing method, the vacuum suction method is used to feed the material. This is to suck out the glass liquid from the blocking brick, cut it and drop it into the forming mold. series of actions. This method is suitable for the manufacture of very large-scale utensils.
(3) Ribbon blowing method
Feed with liquid flow, the rose glass liquid flows out continuously from the leakage hole, is rolled into a strip shape by the roller, and then forms an air bubble on the transmission chain by its own weight and blowing air, and then is closed and blown by the rotating forming die. Made into shape.
The belt blowing method is mainly used to produce light bulb shells and tea cups, etc., and the production capacity is very large. It was first invented and applied to industrial production by Corning Glass Company of the United States, and the production of cookware developed by Corning Corporation in the future almost used this principle.
(four) pressure - blowing method

The drop material is pressed in the initial mold to shape the mouth, and then transferred to the forming mold for blow molding.
Pressure-blowing molding is easy to make the wall thickness of the product evenly distributed, so in addition to being mainly used to produce hollow glass products such as jars, some factories also use this method to produce small-mouth bottles.
The difference between the press-blow method and the blow-blow method is that the bottle mouth and the prototype of the former are pressed by the punch at the same time, while the latter needs to go through pre-core, puff and reverse blowing processes to make the bottle mouth and prototype. The pressure-blow method is developed on the basis of the blow-blow method, and the core is replaced by a punch.
2. Why did the glass suddenly break?
When hot water is poured into the glass, it will break. This is caused by the uneven expansion of the glass after being heated. After the hot water is poured in, the side wall of the cup will be heated and expanded, but the side wall of the cup will be heated unevenly. Yes, the inner side of the cup will heat up immediately, but the outer side will not immediately become hotter, so the inner side will expand rapidly, but the outer part will still maintain the original state, which will lead to inconsistent deformation of the outer and inner glass, and the cup will rupture.
So it does not mean that a thick glass cup is good. A thick cup is more likely to break when heated, but a thin cup is not easy to break. Because a thin cup can quickly transfer heat from the inside to the outside, so the temperature of the cup will be very fast. tends to be uniform, and the degree of expansion and deformation will be smaller; the temperature inside and outside the thick glass is not easy to be consistent quickly. In a short period of time, the inner temperature is high and expands quickly, while the outer side has not yet expanded, so the outer side is pressed by the inner side, so easy to break.
Both sudden heating and sudden cooling can easily break the glass, which is caused by uneven heating of the glass. Contrary to heating, when the cup is suddenly cooled, the outer side of the cup starts to shrink first, but the inner side has not yet contracted. In this way, the inner side is affected The outside pressure will break the glass.
When choosing a glass, you may wish to consider high borosilicate glass, which can support the instantaneous temperature difference from minus 30 degrees to 150 degrees without the glass bursting."