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What is UV?
UV is an abbreviation of Ultraviolet rays. As invisible rays,
it is Hertzian waves in a band outside the purple visible rays,
and the wavelengths are normally divided into following several
branch bands with different characters.
A. Vacuum UV, with wavelengh
10~200nm
B. UV-C, with wavelengh
200~290nm
C. UV-B, with wavelengh 290~320nm
D. UV-A, with wavelengh 320~400nm
E. Visible light, with Wavelengh
400~760nm
UV is used in industrial processing, and UV-A is more
frequently used than any of others.
Theory of UV Solidification
UV solidification makes use of the phototonus of photosensitive
materials. Some molecules of the photosensitive materials get
energy from UV, and step into the excited state, subsequently
decompose themselves into disengaged elements or ions. The disengaged
elements or ions promote the unsaturated organic compounds to
complete polymerization and coalesce etc chemical reactions.
And the process of solidification is completed when the chemical
reactions are over and the photosensitive materials turn into
solid completely.
Disposal methods to the infrared radiation of
UV
Sixty percents of the total power of the Ultraviolet High Pressure
Mercury Lamp are converted to infrared radiation, and the surface
temperature of the lamps maybe rise up to 700~800 o C. To avoid
excessive temperature rising, people pay much attention to adopting
more efficient lamps and multi-lamps systems. So multi-measures
is always taken to cool the lamps, reflecting cups and supporting
materials. Since high temperature is in favor of solidifying
dope, when UV is used to solidify dope, the temperature should
be well controlled so that ones could get nice solidification
with a suitable surface temperature. There are three widely used
measures, one is wind cooling, which is most frequently used
with a little cost; One is water cooling equipped with water
jacket covering the lamps, the effect is nice, but the cost is
much larger; Another is adding optic discs and keeping the solidification
materials free of infrared radiation, it is suitable to the shape
easy-changing product.
The Function of Reflecting Cups
With reflecting cups, it is easy to focus the energy of UV lamps
to the surface of the product. The effect of the reflecting cups
will affect the quality of products directly. The reflecting
cups of Blue Sky Special Lamps Company, are equipped with imported
aluminum alloy flat-plane reflecting sheets, and the reflecting
effect is more nice.
The factors to UV deep solidification:
The UV photosensitive dope is initiated by UV radiation, and
generates disengaged elements or ions. The disengaged elements
or ions react with the unsaturated organic compounds and complete
polymerization and coalesce etc chemical reactions. And the whole
process of solidification is completed when the chemical reactions
are over and the photosensitive materials turn into solid completely.
The factors affecting the deep solidification are show below:
The affect of UV energy
The primary condition
of UV deep solidification, is that the molecules of the UV photosensitive
dope need get enough energy to step into excited state and to
decompose themselves into disengaged elements or ions. The disengaged
elements or ions promote the unsaturated organic compounds to
complete polymerization and coalesce etc chemical reactions,
and the solidification is completed gotten.
If the energy supplied to the UV photosensitive dope is
excessive or deficient, below questions will occur:
a) When the
energy necessary for complete solidification is known, it is
normal that the supplied energy is slightly and reasonably more
than necessary energy.
b) When the energy necessary for complete
solidification is unknown, if one blindly supplies excessive
energy, the energy will be wasted and bad feedbacks to over-solidification
will occur.
c) If the power of UV is deficient, the energy of
UV must be suitable to avoid incomplete solidification.
The affect of the thickness of UV dope
The thickness
of UV dope takes a pivotal affect on the effect of UV solidification.
If the dope thickness is larger than normal value, the solidification
time will be longer with a same power lamp. On one side it will
lower the solidification efficiency, on the other side it will
result in the surface temperature of supporting materials higher
and the supporting materials reshaped. If the dope thickness
is less than normal value, it will result in bad surface appearance
of products. Additionally, the color of dope, temperature, solidification
speed and surface of supporting materials will affect the adjustment
of dope thickness.
The affect of distance
If the distance between
the surface of product and the UV lamp as well as the reflecting
cup is among 7cm and 8cm, the solidification effect will be nice.
But the distance is usually among 10cm and 15cm in accordance
with the supporting materials. When the distance is less than
normal value, the supporting material will be reshaped due to
the high surface temperature of UV lamp. When the distance is
larger than normal value, the surface of supporting materials
is difficult to dry due to less UV energy. Thus, the distance
should be adjusted in accordance with supporting materials, dope
and the power of UV lamp.
The affect of solidification speed
The solidification speed should
be adjusted in accordance with supporting materials, dope and
distance etc. If the solidification speed is higher than normal
speed, the UV dope on supporting materials will be adhesive or
be dry on surface but adhesive inside. If the solidification
is lower, the surface of supporting materials will be aged.
In a word, one should practise in actual processing and sum up
experience frequently to well master the skill.
Failure and Steps
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Failure |
Reason |
Step |
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UV dope solidification incomplete |
Low power density of lamp
Lacking photosensitive
materials
Low temperature or short solidification
time Far distance |
Change a large power lamp
Change dope
Increase solidification time
Higher temperature and adjust
distance |
| |
Dark lamp or twinkle lamp |
High voltage or unsuitable transformer |
Measure voltage and related parameters |
| |
Lamp reshaped |
Bad cooling and high surface temperature |
Increase power of cooling |
| |
Lamp bombed |
High voltage
Dirty on lamp surface
False joint
Circuit short
Mismatched power supply voltage |
Change lamp
Caution dirty
Repair
Repair
Select suitable voltage |
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High temperature of transformer |
High voltage more than 10%
Bad ventilation |
Decrease voltage
Increase ventilation |
| |
Bombed lamp neck |
High voltage or false joint |
Change lamp |
| |
Melted lamp head |
Bad cooling and high temperature |
Increase power of cooling |
| |
High lamp intensity |
Unsuitable transformer
Strong circuit
intensity |
Measure (change)
Change ballast |
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