To know the temperature resistance level of a double-walled tube, first we have to understand what temperature is resistant to temperature, and what types of double-walled tubes are there, and what are the temperature-resistant levels of these double-walled tubes?
What we usually call a temperature-resistant grade is the operating temperature and rated temperature of a double-walled tube. Operating temperature; This temperature is an important parameter through the double-walled tube, the operating temperature is sometimes referred to as the rated temperature, that is, the casing can be normal, continuous operation of the temperature, the first two temperature refers to the processing of double-walled tubes can start to reflect the temperature, we still take φ6 double-walled tube for example, double-walled hot air gun When the temperature begins to reach 84 ℃, the double-walled tube begins to shrink and reflects, and then slowly shrinks to φ5, φ4, when the temperature reaches the final shrinkage temperature of 120 ℃, the double wall tube completely shrinks to φ3, tightly shrinks to the object, and then the process of heating this is over, and then the cover of the double-walled tube on the To carry out normal work, its normal working environment, such as the normal operating temperature of our casing is-55 ℃ to 125 ℃, because we know that many times, products will be sold everywhere, some local environment is relatively cold, some places are relatively hot, then it has a certain scope of application, The nominal temperature of our products indicates that it can be used normally at this temperature, once the normal operating temperature is exceeded, it will not be able to guarantee the life span, may not work properly, we say here the normal temperature heat shrinkable tube is the double-walled tube can play the temperature of insulation protection, beyond this temperature will not necessarily play a role;
Next, let's talk about the temperature resistance levels of double-walled tubes?
When we understand the shrinkage ratio of the heat shrinkable double-walled tube, we have learned the classification of double-walled tubes: environmental protection double-walled tubes, soft thick glue low-temperature shrinkage double-walled tubes, thick-walled double-walled tubes, military standard double-walled tube, automobile wire harness semi-hard double-walled tube, high magnification double-walled tube. corresponding to our double-walled tube temperature-resistant grade is: temperature-resistant 110 ℃ double-walled tube, temperature-resistant 125 ℃ double-walled tube, temperature-resistant 135 ℃ double-walled tube and so on. Of course, if there are special requirements, short-term or long-term need for double-walled tubes to achieve a relatively high temperature, can be specially customized.
Performance of double-walled heat shrinkable tubes:
The characteristics of automobile special heat shrinkable pipe are: thermal shrinkage, double-layer wall, double-layer plastic tube with hot melt adhesive inside.
This double-walled heat shrinkable tube is divided into internal and external two layers, the outer layer is a mixture of low density high pressure polyethylene and ethylene-vinyl acetate co-polymer (EVA), the inner layer is very thin adhesive viscous strong hot-melt sealing resin. When the double-walled heat shrinkable tube is larger than the diameter of the tubing into the tubing surface, positioned and then heated, the double-walled heat shrinkable tube will shrink to a predetermined size, through the inner layer of hot melt glue, the heat shrinkable pipe and tubing tightly connected together, there is no gap between. This tubing protection method can greatly improve the service life of the tubing.
Use of double-walled heat shrinkable tubes:
The initial thermal double-walled heat shrinkable tube shrinkage tube is only a single-walled heat shrinkable tube, mainly used in electrical equipment and refrigeration equipment as the protection of electrical joints. Later, the United States Raychem (Rui Kan) company, the production office dedicated to the automotive industry double-walled heat shrinkable tube. Not only does it provide excellent antiseptic properties, but it also provides protection against the friction parts of the relevant parts, so it is especially suitable for compact small cars, so it is used in a large number of Japanese models in Japan and Korea. In particular, double-walled heat shrinkable tubes have been installed in the chassis of the vehicle, effectively preventing the corrosion of the brake tubing by gravel and muddy water.
In addition, due to the high hardness and wear resistance of the double-layer heat shrinkable tube, a protective layer is formed outside the tubing to avoid direct friction between the steel pipe and other parts, so many foreign car companies stipulate that the interference between parts is allowed in the part where the double-layer heat shrinkable tube is added. Now the market on the small installation of high-power engines and "ABS" and booster steering more and more, is the small space is also more crowded, brake tubing layout has become more and more complex, often between the tubing and between the tubing and related parts interference problems, especially the addition of "ABS" The area of 6 tubing bundled together is difficult to ensure that there is enough clearance between the tubing, resulting in bumps and frictions between the tubing, is indeed a great safety hazard, the application of double-walled heat shrinkable tube so that this problem is solved accordingly.
Quality of double-walled heat shrinkable tubes:
Because the double-walled heat shrinkable tube high temperature heat shrinkable tube plays such an important role, so the quality of the double-walled heat shrinkable tube is crucial, the use of shoddy heat shrinkable pipe will have fatal consequences. For example, there is a temperature interval between the heating shrinkage temperature of a high-quality heat shrinkable tube and the softening melting temperature of the heat shrinkable tube, so that the heat shrinkable tube remains in a good shape during the heating shrinkage process, and the air inside the heat shrinkable tube can be emptied as the heating area moves. But the inferior heat shrinkable tube has softened and melted while heating to the shrinkage temperature, so there is often air enclosed in the heat shrinkable tube, manifested as the bumpy on the surface of the heat shrinkable tube, in order to eliminate the bubbles need to be in the hot shrinkage tube in a softening state when the steel needle eye release gas, because of the shrinkage of the heat shrinkable tube during cooling, These needles form many scars and voids on the surface of the heat shrinkable tube, so the inferior heat shrinkable tube does not reach the protective effect on the tubing.
In addition, qualified heat shrinkable pipe in the heating shrinkage is only in the radial shrinkage, axial basic does not shrink, after processing the finished product consistency is very good, and poor quality heat shrinkable pipe not only axial shrinkage is very large, and even axial elongation, after processing the finished product heat shrinkage tube level is not aligned. In the assembly line often occurs when the tubing clip is not loaded with the phenomenon is often the use of inferior heat shrinkable pipe reasons. In this case, often take the blade elongation out of the heat shrinkable pipe cut off the measures, the surface of the problem solved, in fact, the damage to the tubing is greater, because in the course of operation there will be tubing organic coating scratches, resulting in complete damage to the tubing coating. Therefore, the quality of the heat shrinkable tube is very important.
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