With the enhancement of people's requirements for environmental protection and energy conservation, many advanced energy-saving aluminium extruded profiles and energy-saving processes have been gradually applied in the construction industry. Closely related, aluminum profiles occupy a crucial position in the energy-saving system of the house.
As a key component of thermal insulation aluminum alloy aluminum profiles and curtain walls, thermal insulation strips have also created a new field of aluminum profiles with the application of thermal insulation aluminum alloy aluminum profiles and curtain walls. In short, the thermal insulation aluminum alloy is to divide the original one-piece profile into two parts on the basis of the traditional aluminum alloy, and then two separate parts are connected together by means of mechanical compounding by two thermal insulation strips.
Under natural scattered light, with normal vision (without using a magnifying glass), visual inspection at a distance of 0.5m, the appearance of the insulation strip should be smooth, flat, uniform in color, and there should be no appearance defects on the surface that affect the use, straight strips are not allowed If there is a broken end, the number of broken ends of the coil is not more than 2.
2. Breaking test
Arbitrary sampling is carried out for manual breaking test. When the nylon insulation strip is bent, it can feel good toughness and strength, and it will not break even if the two ends are close together, even if the fracture is slow. Some nylon insulation strips are either brittle Obviously, when there is still a certain distance between the two ends, there will be multi-stage bursting phenomenon, or the toughness is obvious, and the repeated bending is continuous; the PVC insulation strip is very soft, basically has no strength, and will not break after repeated bending.
3. Dimensional accuracy
Using a vernier caliper (micrometer is more accurate) to test the shape accuracy of the thermal insulation strip, it can be found that the size deviation of the nylon thermal insulation strip is less than 0.1mm in different batches or different parts of the same thermal insulation strip, and the parallelism is standard; For some nylon insulation strips or PVC insulation strips, the size deviation of different batches or different parts of the same insulation strip is at least 0.1mm.
1. The change of the heat insulation strip after water absorption and its influence on the strip
After the heat insulation strip is saturated with water, it will have a significant impact on the back spraying of the profile. Since the back spray temperature of the profile reaches about 200°C, the moisture inside the heat insulation strip is difficult to volatilize instantly, so when the heat insulation strip is saturated with water, it will be sprayed back when it is saturated with water. Bubble, resulting in unqualified profiles. Therefore, the water absorption of the heat insulation strip must be strictly controlled for the back spraying process.
Water absorption is an inherent characteristic of nylon 66 thermal insulation strips, so the strips should be threaded as soon as possible after storage, and the prescribed amount of first-in, first-out should be made. Excessive moisture content will affect the efficiency of threading or the back spraying of aluminium extruded sections. It is recommended to store the thermal insulation strip at a temperature of 20°C-30°C and humidity ≤55%. Since nylon 66 is more brittle when it is cold and dry, it is recommended to open the outer packaging of the aluminum profile 3 days before threading. The aluminum profile can absorb a certain amount of moisture, reduce brittleness and improve toughness.
2. The relationship between the placement time of the thermal insulation strip and the size change
The influence of water absorption on the size of nylon 66 thermal insulation strip aluminum profile is still relatively significant, although for the thermal insulation profile with teeth, threading and rolling, the size change of the thermal insulation strip has little effect (only need to adjust the threading, rolling process parameters).
3. Twist the insulation strip
In the production, the twisting phenomenon of the wire rod is often encountered. The main reason is that the heat insulation strip is too tight when it is finished bundling. Secondly, the heat insulation strip is piled up during transportation, which leads to the twisting of the rubber strip, which affects the efficiency of employees in actual production. , but also brings trouble to production.
4. Influence of transverse tensile strength
When used in winter and summer, there is a large temperature difference between the inner and outer cavity profiles of the thermal insulation profiles that make up the thermal insulation aluminum window. This temperature difference will cause different deformation trends between the inner and outer cavity aluminum profiles.
In summer, the temperature of the outer cavity profile is high, causing the outer arch to shrink inward. In winter, the temperature of the outer cavity profile is low, which causes the inner arch to shrink outward. This constant arching stress will cause a large lateral tension in the middle of the insulating profile. If the transverse tensile strength of the thermal insulation strip is low, fracture will occur, resulting in quality problems in the thermal insulation profile.