PPE

New technology, new achievement and development trend of deep welding protective filter

Welding operation is one of the ten special operations specified in the national standard of our country. There are more than 140000 people registered in Shanghai to engage in welding operation. 1n order to prevent these personnel from misoperation and possible production safety accidents in the process of welding operation, high reliability welding eye protection equipment is the necessary personal protective equipment for welders. The welding filter is the key part of the welding eye protection device. 1t can not only provide the operator with a clear field of vision, accurately locate the welding point, but also effectively block the ultraviolet and infrared in the strong light and arc light

Fig. 1 glass solder joint

Fig. 2 automatic dimming filter (AWF)

traditional filters, whether they are commonly known as black glass (Fig. 1) or automatic dimming filter (Fig. 2), have excellent optical properties: nearly 100% UV and infrared filtering performance (Fig. 3). However, most of these filters are made of glass, so their mass is relatively large: ordinary black glass (about 108 mm in size) × 50 mm) is about 40 G; The mass of large window black glass (Fig. 4) even reaches 75 G; The mass of the automatic dimming filter is about 85 G. 1n addition, the glass filter has several disadvantages: first, the glass in the annealing process due to the existence of stress, resulting in the actual use of self explosion cracking phenomenon; Second, the chemical composition of glass is complex, so it is difficult to accurately control its shading number in the process of melting and forming; Third, the glass filter is not shock resistant, fragile and low safety factor; Fourth, glass industry is a high energy consumption and high emission industry, which is not conducive to industrial restructuring and sustainable development. Based on the above weaknesses of glass filters, polycarbonate (PC) filters have appeared in the market (see Figure 5)

Fig. 3 transmittance curves of common black glass filter (left) and AWF (right)

Fig. 4 large window glass solder joint

Fig. 5 PC solder joint

in addition, the impact resistance of PC solder joint has a qualitative leap over glass, and the common glass solder joint has been broken in the national standard drop ball test (45g steel ball falls freely at the height of 1.3m from the solder joint), However, the PC electrode is not damaged at all, and even can resist the impact of high-speed particles. 1ts safety factor and impact resistance level are incomparable with ordinary glass

in recent years, some manufacturers are also developing PC solder pads, but they have not been able to solve the absorption performance of PC solder pads in the infrared band, resulting in that the average transmittance of PC solder pads in the near infrared (12%), especially in the near infrared (23%) exceeds the requirements of national standards (the near infrared is less than 0.1%, and the near infrared is less than 0.25%) (see Figure 6)

Fig. 6 PC solder pad with shading number 10

it is gratifying that in recent years, there are new developed PC solder pads and PC gold-plated solder pads (see Fig. 7) in China, which not only have excellent impact resistance, but also have the same UV-1R light filtering performance as glass solder pads (see Fig. 8). The average transmittance of N1R and mid N1R is two orders of magnitude lower than the national standard, and it can also meet the requirements of European standard en169 and American Standard ANS1 Z87.1

Fig.8 spectral transmission of gold-plated PC solder pad with shading number 10

the successful R & D of PC solder pad not only breaks the monopoly of a few foreign enterprises, but also improves the intrinsic safety of welding, and promotes the wide use of PC solder pad in welding operation, laying a good foundation

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