POLYURETHANE FOAMING MACHINE (FOAMING THEORY, SELECTION METHOD)

About the basic knowledge of polyurethane foaming machine series What kind of equipment is the foaming machine?

Foaming machine, also known as foam generator, is the simplest equipment to make foamed products. The foaming machine is a foaming equipment that can make a certain concentration of foaming agent into a foaming solution. The foaming agent itself cannot automatically become foam, it must pass the mechanical action of the foaming machine to become foam. The foaming machine and the foaming agent are a technical system that cooperates with each other and cannot play a role alone.

The foaming machine is actually an air-entraining machine, which introduces air into the foaming agent aqueous solution to evenly disperse it to achieve the largest possible contact surface between the liquid and the gas, so that the surface active substances in the foaming agent form a double electric on the surface of the liquid film. Layer and surround the air, forming a bubble. Therefore, the foaming machine is also equivalent to a foaming machine, which is equivalent to mixing the foaming agent aqueous solution with air to form bubbles.

The main body of polyurethane foam products is foam, so the foaming machine for making foam has become the key equipment and host for the production of foam products. Talk about the development and history of foaming machines. Foaming machines first appeared in foreign countries, and their original models used impellers to rotate at a high speed to make foam, so they were also called "bubbling machines." Later, with the continuous advancement of technology, the technical content of the foaming machine continued to increase, and new models continued to appear, forming different technical systems. my country began to use foaming machines as early as the 1950s, but instead of special foaming models, mortar mixers were used. That is, the foaming agent is directly added to the mortar mixer or concrete mixer, and the foaming agent is mixed with the mortar or concrete to generate foam. Around the 1970s, special foaming agents, namely high-speed impeller foaming machines, began to appear. In the future, the technology has been continuously upgraded and replaced, and now it has developed into a third-generation model with high-pressure inflation as the main body, which can basically meet the needs of foam concrete. Regarding the selection method of polyurethane foaming machine, there are many types of polyurethane foaming machines appearing on the market. There are countless foaming machines of various brands, shapes and names, and there are also many types of foaming machines with new brands and new names. Keep rolling out. The numerous models have dazzled the producers, so that they choose the wrong model. Now let's talk about the selection method of foaming machine.

1. Fully understand the equipment type of polyurethane foaming machine (Although the basic principle of foaming machine is to introduce gas into the foaming agent aqueous solution, different types of foaming machines have different ways of introducing gas.)

2. Carefully master the basic technical parameters of the polyurethane foaming machine (For the producer, understand several important technical parameters of the foaming machine to determine whether it meets their own production requirements.)

3. Carefully understand the foaming quality of the equipment (to determine the foaming quality of the foaming machine, three aspects should be the main factors, namely foam fineness, foam uniformity, and foam bleeding.) When purchasing equipment, "precise", " Uniformity, stability, and foam quality are important considerations. The principle of polyurethane foaming machine No matter what kind of foaming machine equipment, the basic principle of foaming is to introduce air into the blowing agent solution. The change of various models is that the way of introducing gas is different, so the effect is also different. There are two necessary factors for the formation of foam, one is foaming agent solution, and the other is air, both of which are indispensable. Without the blowing agent solution, the liquid film surrounding the gas would not form and there would be no bubbles. And without gas, foaming agent solution alone cannot form bubbles. In the bubble formation system, the blowing agent solution is the dispersion medium, the gas is the dispersed phase, and the gas is dispersed in the liquid to form bubbles, and then numerous bubbles form the foam. In addition to the important factor of blowing agent performance, the introduction of gas into the blowing agent solution is another important factor. The introduction of gas into the liquid must be done by the foaming machine, that is, the foaming machine adopts a certain method to introduce the gas into the liquid.

Polyurethane foaming machines are divided into polyurethane high-pressure foaming machines and low-pressure foaming machines. The raw liquids of the two components of A and B are accurately proportioned and stirred at high speed. Two high-precision metering pumps are used to transport the A and B components to the mixing head. After high-speed and intensive stirring, the material and liquid are evenly sprayed out to form the desired product. In terms of power, it can be classified into: high-speed impeller type, high-pressure air type, blast medium and low pressure type. A complete polyurethane foaming machine consists of the following systems: material flow system, metering system, gas path system, heating system, cleaning system, mixing device.

Production process of polyurethane foaming machine

1. Feeding and mixing: Add a certain amount of cement, foaming agent, and foam stabilizer to the mixer through the feeding system, and dry-mix for 30 seconds; 　　

2. Stirring: Add a certain amount of warm water to the blender and stir for 2 minutes; add a quantitative amount of foaming agent to the blender and stir for 8-15 seconds;

3. Injection molding and foaming: the slurry is then injected into the mold to foam, and the foaming process is about 3-5 minutes; 　　

4. Initial curing: After the injection molding is completed, let it stand for several hours for initial curing;

5. Demoulding: After the initial setting of the foamed cement insulation board is completed, it can be released when it has the initial strength; 　　 6. Cutting: The foamed cement insulation board with a certain strength can be cut after demoulding, and the cutting specifications are according to needs Adjust the cutting blade;

7. Finished product curing: The curing age of foamed cement insulation board should not be less than 7 days.

Application range of polyurethane foaming equipment Currently, polyurethane foam is widely used. Soft foam plastics are widely used in various cushioning materials and sound insulation materials for furniture and transportation; rigid foam plastics are mainly used for household appliances heat insulation layer, roof insulation and waterproof spray foam, pipe insulation materials, building boards, refrigerated vehicles and cold storage Heat insulation materials, etc.; semi-rigid foam plastics are used in automobile dashboards, steering wheels, etc. There are various types of foam plastic composite materials (two-component premix) on the market, which are mainly used for (cold curing) high resilience foam, semi-rigid foam, casting and spraying rigid foam, etc.