The production process of glass bottles and jars
How are glass jars made? The production process of glass bottle includes: batching, melting, forming, annealing and other processes. They are introduced as follows:
1. Ingredients
According to the designed material list, the various raw materials will be weighed in a mixer mixed evenly. The main raw materials of glass jars are: quartz sand, limestone, feldspar, soda ash, boric acid and so on.
2. Melting
The prepared raw materials through high temperature heating, forming a uniform bubble-free glass liquid. This is a very complex physical and chemical process. The melting of glass bottles and jars is carried out in the melting kiln. There are two main types of melting kiln: one is the crucible kiln, the glass material is held in the crucible, outside the crucible heating. Small crucible kilns only have one crucible, large ones can have as many as 20 crucible. Crucible kiln is gap production, now only optical glass and color glass use crucible kiln production. The other is the pool kiln, the glass material is melted in the kiln, and the open fire is heated on the surface of the glass liquid. Temperature of the melted glass bottles in 1300 ~ 1600 ゜ c. Most are heated by flame, but a small number are heated by electric current, which is called electric melting kiln. Now, the pond kiln is continuously produced, and the small one can be several meters, and the big one can be as big as more than 400 meters.
3. Forming
Is to melt the liquid glass into a fixed shape of solid products. Forming must be done within a certain temperature range. This is a cooling process in which glass first changes from a viscous liquid to a plastic state and then to a brittle solid state. Forming methods can be divided into two categories: artificial forming and mechanical forming.
A. Artificial shape.
Or (1) blowing, with a nickel-chrome alloy blow pipe, pick a ball of glass in the mold while rotating while blowing. It is mainly used to form glass bubbles, glass bottles, balls (for glasses) and so on.
(2) Drawing, after blowing into a small bubble, another worker with the top plate stick, two people while blowing while pulling mainly used to make glass tube or rod.
(3) Pressing, select a group of glass, cut it with scissors to make it fall into the concave die, and then press with a punch die. Mainly used to form cups, plates, etc.
(4) Free forming, after picking materials with pliers, scissors, tweezers and other tools directly into crafts.
B. Mechanical forming.
Because the artificial forming labor intensity, high temperature, poor conditions, so, in addition to free forming, most have been replaced by mechanical forming. Mechanical forming in addition to pressing, blowing, drawing,
And (1) calendering method, used to produce thick flat glass, carved glass, wire glass and so on.
(2) casting method to produce optical glass.
(3) Centrifugal casting method, used for the manufacture of large-diameter glass tubes, utensils and large-capacity reaction POTS. This involves injecting a glass melt into a mold that is spinning at high speed. Due to centrifugal force, the glass is pressed against the wall of the mold. The rotation continues until the glass hardens.
(4) sintering method for the production of foam glass. It is a foaming agent added to the glass powder, heated in a metal mold with a cover. The glass forms a lot of closed bubbles in the heating process, which is a good insulation and sound insulation material. In addition, the forming of flat glass has vertical lead up method, flat drawing method and float method. Float method is the method of making glass liquid flow float on the surface of molten metal (tin) to form flat glass. Its main advantages are high quality glass (smooth, smooth), fast pulling speed and large yield.
4. Annealed
Glass undergoes intense temperature and shape changes during forming, which leave a thermal stress in the glass. This thermal stress will reduce the strength and thermal stability of glass products. If it is cooled directly, it is likely to break itself (commonly known as cold explosion of glass) during the cooling process or later during storage, transportation and use. In order to eliminate cold explosion, glass products must be annealed after forming. Annealing is the process of holding heat or cooling it slowly over a certain temperature range for a period of time in order to eliminate or reduce the thermal stress in the glass to an allowable value.
In addition, some glass products can be hardened to increase their strength. Including: physical hardening (hardening), used for thicker glasses, tabletop glass, car windshield, etc.; And chemical rigid (ion exchange), used for watch cover glass, aviation glass, etc. The principle of rigidity is to create compressive stress in the surface layer of glass to increase its strength.