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In our production, continuous glass fiber production processes are mainly two types of crucible drawing process and pool kiln drawing process. At present, most of the pool kiln wire drawing process is used on the market. Today, let’s talk about these two drawing processes.

1. Crucible Far Drawing Process

The crucible drawing process is a kind of secondary molding process, which is mainly to heat the glass raw material until it is molten, and then make the molten liquid into a spherical object. The resulting balls are melted again and drawn into filaments. However, this method also has its shortcomings that cannot be ignored, such as a large amount of consumption in production, unstable products, and low yields. The reason is not only because the inherent capacity of the crucible wire drawing process is small, the process is not easy to be stable, but also has a great relationship with the backward control technology of the production process. Therefore, for now, the product controlled by the crucible wire drawing process, the control technology has the most significant impact on the product quality.

Glass fiber process flow chart

Generally speaking, the control objects of the crucible are mainly divided into three aspects: electrofusion control, leakage plate control and ball addition control. In electrofusion control, people generally use constant current instruments, but some use constant voltage control, both of which are acceptable. In the leakage plate control, people mostly use constant temperature control in daily life and production, but some also use constant temperature control. For ball control, people are more inclined to intermittent ball control. In people’s daily production, these three methods are enough, but for glass fiber spun yarns with special requirements, these control methods still have some shortcomings, such as the control accuracy of the leakage plate current and voltage is not easy to grasp , The temperature of the bushing fluctuates greatly, and the density of the produced yarn fluctuates greatly. Or some field application instruments are not well combined with the production process, and there is no targeted control method based on the characteristics of the crucible method. Or it is prone to failure and the stability is not very good. The above examples show the need for precise control, careful research, and efforts to improve the quality of glass fiber products in production and life.

1.1. Main links of control technology

1.1.1. Electrofusion control

First of all, it is necessary to clearly ensure that the temperature of the liquid flowing into the leakage plate remains uniform and stable, and to ensure the correct and reasonable structure of the crucible, the arrangement of the electrodes, and the position and method of adding the ball. Therefore, in electrofusion control, the most important thing is to ensure the stability of the control system. The electrofusion control system adopts an intelligent controller, current transmitter and voltage regulator, etc. According to the actual situation, the instrument with 4 effective digits is used to reduce the cost, and the current adopts the current transmitter with an independent effective value. In actual production, according to the effect, in the use of this system for constant current control, on the basis of more mature and reasonable process conditions, the temperature of the liquid flowing into the liquid tank can be controlled within ± 2 degrees Celsius, so the research found that it can be controlled. It has good performance and is close to the wire drawing process of the pool kiln.

1.1.2. Blind plate control

In order to ensure the effective control of the leakage plate, the devices used are all constant temperature and constant pressure and relatively stable in nature. In order to make the output power reach the required value, a regulator with better performance is used, which replaces the traditional adjustable The thyristor trigger loop; in order to ensure that the temperature accuracy of the leakage plate is high and the amplitude of the periodic oscillation is small, a 5-bit temperature controller with high precision is used. The use of an independent high-precision RMS transformer ensures that the electrical signal is not distorted even during constant temperature control, and the system has a high steady state.

1.1.3 Ball control

In the current production, the intermittent ball addition control of the crucible wire drawing process is one of the most important factors affecting the temperature in normal production. The periodic ball-adding control will break the temperature balance in the system, causing the temperature balance in the system to be broken again and again and re-adjusted again and again, making the temperature fluctuation in the system larger and the temperature accuracy difficult to control. Regarding how to solve and improve the problem of intermittent charging, becoming continuous charging is another important aspect to improve and improve the stability of the system. Because if the method of kiln liquid control is more expensive and cannot be popularized in daily production and life, people have made great efforts to innovate and put forward a new method. The ball method is changed to continuous non-uniform ball addition. , you can overcome the shortcomings of the original system. During wire drawing, in order to reduce the temperature fluctuation in the furnace, the contact state between the probe and the liquid surface is changed to adjust the speed of adding the ball. Through the alarm protection of the output meter, the process of adding the ball is guaranteed to be safe and reliable. Accurate and suitable high and low speed adjustment can ensure that liquid fluctuations are kept small. Through these transformations, it is ensured that the system can make the high-count yarn count fluctuate within a small range under the control mode of constant voltage and constant current.

2. Pool kiln wire drawing process

The main raw material of the pool kiln wire drawing process is pyrophyllite. In the kiln, the pyrophyllite and other ingredients are heated until they are melted. The pyrophyllite and other raw materials are heated and melted into a glass solution in the kiln, and then drawn into silk. The glass fiber produced by this process already accounts for more than 90% of the total global output.

2.1 Pool kiln wire drawing process

The process of wire drawing in pool kiln is that the bulk raw materials enter the factory, and then become qualified raw materials through a series of processes such as crushing, pulverization, and screening, and then transported to the large silo, weighed in the large silo, and mixed the ingredients evenly , after being transported to the kiln head silo, and then the batch material is fed into the unit melting kiln by the screw feeder to be melted and made into molten glass. After the molten glass is melted and flows out of the unit melting furnace, it immediately enters the main passage (also called clarification and homogenization or adjustment passage) for further clarification and homogenization, and then passes through the transition passage (also called the distribution passage) and the working passage ( Also known as forming channel), flow into the groove, and flow out through multiple rows of porous platinum bushings to become fibers. Finally, it is cooled by a cooler, coated by a monofilament oiler, and then drawn by a rotary wire drawing machine to make a fiberglass roving bobbin.

3.Process flow chart

4. Process equipment

4.1 Qualified powder preparation

The bulk raw materials entering the factory must be crushed, pulverized and screened into qualified powders. Main equipment: crusher, mechanical vibrating screen.

4.2 Batch preparation

The batching production line consists of three parts: pneumatic conveying and feeding system, electronic weighing system and pneumatic mixing conveying system. Main equipment: Pneumatic conveying feeding system and batch material weighing and mixing conveying system.

4.3 Glass melting

The so-called melting process of glass is the process of selecting suitable ingredients to make glass liquid by heating at high temperature, but the glass liquid mentioned here must be uniform and stable. In production, the melting of glass is very important, and it has a very close relationship with the output, quality, cost, yield, fuel consumption, and furnace life of the finished product. Main equipment: kiln and kiln equipment, electric heating system, combustion system, kiln cooling fan, pressure sensor, etc.

4.4 Fiber forming

Fiber molding is a process in which the glass liquid is made into glass fiber strands. The glass liquid enters the porous leakage plate and flows out. Main equipment: fiber forming room, glass fiber drawing machine, drying furnace, bushing, automatic conveying device of raw yarn tube, winder, packaging system, etc.

4.5 Preparation of sizing agent

The sizing agent is prepared with epoxy emulsion, polyurethane emulsion, lubricant, antistatic agent and various coupling agents as raw materials and adding water. The preparation process needs to be heated by jacketed steam, and deionized water is generally accepted as the preparation water. The prepared sizing agent enters the circulation tank through the layer-by-layer process. The main function of the circulation tank is to circulate, which can make the sizing agent recycle and reuse, save materials and protect the environment. Main equipment: Wetting agent dispensing system.

5. Glass fiber safety protection

Airtight dust source: mainly the airtightness of production machinery, including overall airtightness and partial airtightness.

Dust removal and ventilation: First, an open space must be selected, and then an exhaust air and dust removal device must be installed in this place to discharge the dust.

Wet operation: The so-called wet operation is to force the dust to be in a humid environment, we can wet the material in advance, or sprinkle water in the working space. These methods are all beneficial to reduce dust.

Personal protection: The dust removal of the external environment is very important, but your own protection cannot be ignored. When working, wear protective clothing and dust masks as required. Once the dust comes into contact with the skin, immediately rinse with water. If the dust gets into the eyes, emergency treatment should be carried out, and then immediately go to the hospital for medical treatment. , and be careful not to inhale the dust.

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