safety net is a kind of labor protection equipment to prevent falling injury, which can be used in all kinds of construction sites, especially in high-rise buildings. 1t can effectively prevent the falling injury of people and objects, prevent the fire caused by welding sparks, reduce the noise and dust pollution, achieve the effect of civilized construction, protect the environment and beautify the city, and has been widely used at home and abroad< At present, there are three types of safety net widely used in China: safety flat net, safety vertical net and dense mesh safety vertical net. The placement plane of the safety horizontal net is parallel to or at an angle with the horizontal plane to catch the falling person or object. The placement plane of the safety vertical net and the dense mesh safety vertical net is vertical to the horizontal plane to surround the high-altitude working surface and block the person or falling object. The dense mesh safety vertical net also has the function of preventing small tools used by operators from falling down and hurting people< 1n 1988, the former Ministry of labor and personnel promulgated the implementation rules for the production license of special labor protection articles, and began to formally include the labor protection articles that directly endanger personal safety and health into the scope of production license. At present, the AQS1Q is responsible for the production license and quality supervision of safety net, and the State Administration of work safety is responsible for the production license and labor safety certification< (1) product quality. The production process of flat net and vertical net is usually as follows: raw materials > wire drawing > thread combination > twisting rope > net weaving (mechanical or manual) > finishing > inspection > packaging > warehousing > sales; The production process of dense mesh safety vertical net is usually raw material > wire drawing > net weaving (machinery) > sewing > nailing > inspection > packaging > warehousing > sales; The key link is drawing and weaving
in the 1950s, cotton, hemp, brown and other natural fibers were mainly used for flat and vertical nets, and chemical fibers were gradually used after the 1960s, but the product quality level was uneven and the specifications were various, which caused great inconvenience to the use. 1n 1983, we began to organize the formulation of safety net standards, which regulated the safety net product market well. The product specifications tended to be unified, and the quality was greatly improved. With the rapid development of economy, the quality requirements of safety net are higher and higher, and the standards have been constantly revised, but the product quality problems have never stopped
dense mesh vertical safety net is a kind of fall protection equipment used in developed countries in the early 1980s, especially in the construction industry of Japan and the United Kingdom, and the corresponding product standards have been formulated and implemented. This kind of products entered the Chinese market in the late 1980s. Compared with the traditional safety flat net and vertical net, the dense mesh safety vertical net has the advantages of high mechanization, high production efficiency, easy to control the product quality, and relatively stable quality, especially its flame retardant performance, penetration resistance, dust prevention, anti-corrosion and anti-corrosion Beautifying the working environment and other characteristics are incomparable between the safety flat net and the safety vertical net. At present, dense mesh safety net has become the mainstream of all kinds of safety net products, almost replacing the traditional safety net
at present, 13 items, such as rope spacing and length, rope spacing, side rope breaking strength, rope breaking strength, rope breaking strength, flame retardant performance and impact resistance, are mainly evaluated for horizontal and vertical nets; Breaking strength of dense mesh vertical safety net products × There are 12 items, such as breaking elongation, trapezoidal tearing strength, eye opening buckle strength, flame retardancy, penetration resistance and impact resistance. Through many years of national product quality supervision and inspection, the results are as follows:
1. GB 5725-2009 requires that the breaking strength of the side rope is greater than or equal to 7000n, and it has enough strength to fix the net body; The breaking strength of the net rope is more than 3000n, which can effectively prevent people from falling and not being torn; The breaking strength of the rope is less than or equal to 3000n, so as to prevent the falling body from being hurt by the rope and play a necessary buffer role. One is that the diameter of side rope and net rope is reduced in order to reduce the cost. The other is that the structure design is unreasonable, resulting in disqualification