Welding goggles are composed of frames, filters and protective sheets, and their structure must meet the following requirements:
1. The lens should not fall off due to the heating of the frame;
2. The parts touching the face must not have corners;
3. Parts that come into contact with the skin must not have an allergic stimulus to the skin. Goggles are available in ordinary glasses, front-mounted mirrors, and anti-test glasses.
2. Technical performance
The technical performance requirements of welding goggles should meet the requirements of GB3609, 1-83.
1. Standard sizes
The diameter of the round frame of the frame is not less than 50mm.
The length and width of the filter is 50mm × 108mm, and the error is (0.8mm, thickness 2mm ~ 3.8mm).
The length and width requirements of the protection sheet are the same as those of the filter, and the thickness is not less than 2mm.
2. Filter quality
(1) The appearance quality filter is to protect the user's eyes, and the eyes are a very precise optical instrument, so the lens must have smoothness, and there should be no visible scratches, ripples, bubbles, foreign objects and color Equal defects. If these defects exist, the optical performance will be affected, the vision will be unclear, the work will be affected, and the effect of protecting the eyes will be lost.
(2) Heat resistance Because the arc temperature of welding and high-temperature cutting operations will reach a very high temperature (more than a few thousand degrees Celsius), forming a different environment for civilian glasses, so the filter should be resistant to a certain temperature. It is required to put the filter into 67 ° C (2 ° C water for 3 minutes) and then take it out immediately and then put it in 4 ° C (1 ° C water, it should be qualified if there is no abnormality.
(3) Strength performance
There may be dangerous objects splashing into the eyes during the welding process, so the filter should have a certain strength. Most foreign countries stipulate that steel balls that fall freely from a height of 1 meter or 1.2 meters are used for inspection. The standard stipulates that 16 grams of steel balls fall freely from the height of 0.6m to the center of the filter, and the filter has no cracks. If a protective sheet (three-layer lens) is added before and after the filter, the height of the steel ball is increased to 1.2m and dropped three times in a row, and no damage is considered qualified.
(4) Optical performance
When the light incident perpendicularly into the first face of the prism is refracted from the second face, the amount of split shot due to the action of the prism is parallelism. Measured at a distance of 10m from the second surface (the distance from the scale from the surface of the sample to the light) if the standard is 1cm higher than the standard, it is called a prism degree. Less than 1/6 prism degree is qualified.
The parallelism can also be determined by directly measuring the thickness of the lens. The standard stipulates that the filter size error is:
Thickness difference in the length direction is less than L length difference = 0.389mm
Thickness difference in width direction is less than L width difference = 0.180mm
Measure the thickness of four corners. The average of the thickness of two corners of one side is the thickness of this side. The difference between the thicknesses of the opposite sides should be less than the value specified above.
No diopter of the filter is allowed. Because normal people wear goggles, if the diopter glasses are blurred, there will be symptoms of dizziness, which affects work and health. Therefore, the standard stipulates that it must be below 0.125D no matter at any warp.
c, shading number
It is a number indicating the shading ability of the filter. There are 19 numbers from small to large. Visible light, infrared and infrared transmittance are inversely proportional to the size of the shading number, that is, the small shading number has a large transmittance, and the large shading number has a small transmittance.
The shading number is related to the visible light transmittance, and the shading number can be calculated by the following formula: S = 1 + 7 / 3lg1 / (
S in the formula-shading number;
(――Visible light transmittance.
d. Permittance of invisible light
Ultraviolet radiation is the main cause of acute electro-optic ophthalmia. Glass sheets of various colors can absorb ultraviolet rays below 313nm, but can penetrate the wavelength range from 313nm to 400nm, and ultraviolet rays in this range are the most harmful to the eyes. For this reason, the allowable transmittance of ultraviolet light at two wavelengths of 313nm and 365nm is specified in this standard, which is consistent with the international standard ISO / 4850.
The infrared part stipulates 780nm to 2000nm, which is also based on the possible damage to the eyes caused by the infrared wavelength generated during welding. Especially, the near infrared range of 780-1300nm has the greatest impact on the human eye, followed by the mid-near infrared range of 1300-2000mm. The allowable transmittance of these two parts is consistent with the requirements of ISO4850.
The color of the filter is from the physiological point of view of the human eye. If you focus on one of the blue, green, red, and three colors for a long time, your eyes will soon feel tired. Except for the green part, blue and red form purple and orange-red light, respectively, when observing such light, the human eye will have a significant hue difference. In the welding arc and its vicinity, the red image and the blue image will interlace into a double image, making the eyes feel extremely uncomfortable. Therefore, the specified color can not be a single color, to mix colors, preferably brown, dark green, or gray.
f. UV resistance
This requires that the filter should be stable under strong ultraviolet radiation. The standard stipulates that the filter should be tested at a distance of 200cm from a 450W high-pressure xenon lamp and irradiated for 50 hours, and the transmittance and intensity should meet the requirements.
3. Protective film
The protective sheet is made of colorless and transparent glass, and the requirements are as follows:
(1) The transmittance of visible light is not less than 89%:
(2) The parallelism is the same as the filter requirements.
(1) Heat resistance
Place the frame in a thermostat and heat to 60 ° C (2 ° C, take it out after 30 minutes and cool it at room temperature. Observe that no deformation is acceptable.
Mainly aimed at the metal parts of goggles. It is stipulated that the oil dirt on the surface of the metal parts is cleaned and placed in a boiled 10% salt solution for 15 minutes, and the liquid on the surface is not wiped off. After drying at room temperature for 24 hours, it is washed with warm water and the surface should be observed without corrosion.
(3) Flame resistance
Due to the high temperature generated in welding or gas cutting, as well as the splash of sparks and hot objects, the frame should have a certain flame resistance. The specified burning speed should be less than 76mm / min.
3. Use of welding goggles
1. Use of filters
When using a filter with a larger shading number, you can use a combination of 2 filters with a smaller shading number, and the effect is the same. It can be calculated according to the following formula:
N = (n1 + n2) -1
N in the formula-combined shading number;
n1, n2――For each filter, the shading number.
For example: n1 is 8, n2 is 3, then N = (8 + 3) -1 = 10 (shading number)
2. Use of protective sheet
During the welding operation, a new protective sheet should be replaced at least once every 8h to protect the eyesight of the operator.
4. Quality inspection and determination principles of welding goggles
Welding goggles are products with mandatory production licenses, and their quality must comply with the requirements of the national standard GB3609. The inspection requirements are as follows:
1. Number of samples
Each color number is 3 pieces. When the number is less than 3, the number should not be less than 10 pieces.
5 pay for auxiliary glasses.
2. The inspection items shall be carried out according to regulations.
3. Comprehensive judgment principle:
If there is one failure, it is judged as failure.