【Depth】New technology, new achievements and development trend of welding protection filter

The welding operation is one of the ten special operations stipulated by our country's national standards. There are as many as 140,000 people involved in welding operations in Shanghai alone. In order to prevent misoperation of these personnel during the welding operation and possible production safety accidents, high-reliability welding eye protection equipment is a necessary personal protective equipment for welding workers. The welding filter is a key component of the welding eye protection. It not only provides the operator with a clear vision, can accurately locate the welding spot, but also can effectively block the ultraviolet and infrared rays in strong light and arc light.

Figure 1 Glass Solder

Figure 2 Auto-differential filter (AWF)

Traditional filters, whether they are commonly known as black glass (Figure 1) or automatic welding filter (AWF, Auto welding filter, Figure 2), they all have very good optical properties: nearly 100% of the UV And infrared filter performance (Figure 3). However, these filters are mostly made of glass, so their mass is relatively large: the mass of ordinary black glass (about 108×50 mm) is about 40 g; the quality of large window black glass (Figure 4) even reaches 75 g; the quality of the auto-darkening filter is approximately 85 g. In addition, the glass filter has several drawbacks: First, due to the presence of stress in the annealing process of the glass, the self-exploding and cracking phenomenon is easily caused in practical use; second, the chemical composition of the glass is complex, and the glass is melted and formed. It is difficult to accurately control the shading number in the process. Third, the glass filter is not resistant to impact, fragile, and has a low safety factor. Fourth, the glass industry is a high-energy-consuming, high-emissions industry that is not conducive to industrial restructuring and sustainable development. development of. Based on the above weaknesses of glass filters, polycarbonate (PC) filters began to appear on the market (see Figure 5).

Figure 3 Transmittance curves of ordinary black glass filters (left) and AWF (right)

Figure 4 large window glass welding pads

Figure 5 PC welding pads

In addition, the impact resistance of PC pads has been a quantum leap over that of glass slides, which have been broken during the ball drop test of the national standard (45g steel balls fall freely at a height of 1.3m from the welding pads), while the PC pads have been broken. Without any damage, it can even prevent the impact of high-speed particles, and its safety factor and impact resistance are unmatched by ordinary glass.

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

Fig. 6 PC electric shield with No. 10 light shield

It is gratifying to note that in recent years, there have been newly developed PC electrical pads and PC gold plated electrical pads (see Figure 7), which not only have excellent impact resistance, but also have the same UV-ray-infrared light performance as glass pads ( See Figure 8). The performance index of the near-infrared and mid-infrared average transmittance is two orders of magnitude smaller than the national standard, and it can also meet the requirements of European standard EN169 and American standard ANSI Z87.1.

Figure 8 Spectral transmission of gold-plated PC electrode pads with a light-shielded number 10

The successful development of PC welding pads not only broke the monopoly of a few foreign companies, but also improved the intrinsic safety of welding and promoted the widespread use of PC welding pads in welding operations, laying a good foundation.