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LED industry in one of the problems of heat transfer – the concept of (-)thermal resistance(-) abuse
LED due to its energy-saving, environmental protection, long life, to be recognized as human beings of the next generation of
lighting technology, LED lighting applications, the popularity of the biggest impediment to the high price of LED lights, the high
price is due to the heat problem.
The heat belongs to part of the heat transfer. The human heat transfer research has centuries of history, the last century, 60 to
70 years on heat transfer research, the peak of its main driving force is the human development needs of the aerospace. That era,
the field of heat transfer technology has brought together many talents, a lot of celebrities, people on the heat transfer
research interest gradually decreases as the heat transfer and technology become more sophisticated, very little heat transfer and
technical professionals. heat transfer and technology is very mature, like like ripe fruit fell to the ground covered by leaves,
people now see.
LED cooling, the temperature is not high (less than 100 ° C), is a normal temperature and heat transfer, phase transitions and
complex process, power is not a single LED chip is 1 ~ 2W, in terms of heat transfer and technology, the LED cooling is very
simple, involving only a very small part of the heat transfer – heat transfer thermal conductivity and convective heat (mainly air
natural convection heat transfer), thermal conductivity, heat transfer can use off-the-shelf heat transfer computer software, and
get very accurate solution.
Simple questions for the LED heat dissipation is complicated reasons: the knowledge gaps, has a mature knowledge of heat transfer
involved in the LED heat of little people do not have to unplug the leaves on the ground, picking up the ripe fruit of
transplantation, mature human knowledge of heat transfer to the electronics industry, but re-breeding, planting trees.
LED industry (or heat transfer in the electronics industry) that is to start all over again, from the industry to create a new
term: "active cooling" and "passive cooling", you can illustrate this point. Industry are very familiar with the term "heat sink",
it sounds like I do not know what it means in English "Sink" in the heat transfer and technology is very rare term. Existing
mature heat transfer school called "orthodox heat transfer, heat transfer in the LED industry (electronics industry) known as the"
industry heat transfer ideas and concepts of the industry, heat transfer analysis and orthodox heat transfer is inconsistent This
article from the industry application of the concept of "thermal resistance to heat transfer problems in the LED industry.
"Thermal resistance" concept of abuse in the industry, heat transfer, clearly demonstrated the stigma of the electronic circuitry,
the LED heat dissipation process is decomposed into several series and parallel thermal resistance components, the LED shown in
Figure 1 cooling process of thermal resistance analysis chart, very common, like the resistance in the circuit in the LED
industry.
In electronic circuits, the series resistance in the circuit, regardless of front and rear; about the parallel circuit of
resistance regardless of the heat transfer process is not the case. In electronic circuits: series and parallel resistance
relationship is very clear, the resistor, the basic man-made, or instruments can be directly measured or deduced. But in the heat
transfer process, especially in LED cooling process, there is no clear and the thermal resistance of series and parallel
relationship, can not simply calculate the thermal resistance values, if we adopt the "thermal resistance" method to calculate the
analysis, it will be a simple problem complicated. Few orthodox heat transfer with the concept of "thermal resistance" to analyze
the heat transfer process.
Laser welding to complement the introduction of molds for wire
Laser welding of light and heat energy is highly concentrated in very small (0.2mm ~ 2.0mm) spot in the moment (0.5ms ~ 20ms) wire and die base metal to melt. Melt cooling the welded part of the microstructure with the mold base metal, you can ensure welding quality; and if not, may occur trachoma, cracks, or adhesive is not strong and fall off.
Welding consumables selection affect the welding quality: 1. If you select a mold base metal of the metal strips to laser welding, the microstructure of the molten metal will be inconsistent with the mold base metal, weld quality from the impact.
If you choose to stainless steel wire, or close to the stainless steel material when the laser welding with the same above problem, and can not guarantee that the hardness after welding. Less because the carbon content of stainless steel, low hardness after welding, the welding of easy to wear.
German imports of wire, there are different models for different mold materials. However, laser welding is different from arc welding, laser welding is a highly concentrated light and heat welding wire model choice is not very strict, as long as welding followed by the base metal fusion splicing and consistent hardness can be to achieve good weld quality.
The preservation of the wire: As the laser welding alloy material, stainless steel wire, save the poor will be likely to rust. Some laser welding a thin layer of rust-proof material on the surface plating, but the anti-rust plated layer is too thick, otherwise it will affect the welding quality, because this anti-rust layer is equivalent to impurities in the welding process. The welding wire of the mirror mold, but not suitable for anti-rust layer plating.
Wire to use to seal the bag, put the moisture beads, stored in a dry environment. On the long-term air-conditioned environment, can be stored for six months to a year will not rust.
If the wire rust, surface rust with sandpaper layer hit bright, you can use without affecting the welding quality.
The more common German wire model is MOLD10, MOLD50, MOLD55, and MOLD90 which diameter is 0.3mm, the common wire of 0.4mm and 0.5mm, stock inventory in the country. If you want to order a special wire is from the German order, depending on order quantity and delivery in a week to three weeks.
Wire model of choice, mainly based on the use and hardness of the mold. However, each use of laser welding parameters to the wire when choosing a wire model, instructions for use as a reference, based on the laser welding parameters and operating habits.
Silver copper-zinc-tin alloy
Applications and features:
The products used in refrigeration, mechanical and electrical, mechanical, glasses, appliances, gold and silver products, instruments and stainless steel
workpiece brazing for brazing copper and copper alloys and steel workpiece. Good fluidity, low melting temperature of the brazed joints smooth, high
mechanical strength, joints, products to adapt to all the brazing method in addition to vacuum furnace brazing. Brazing must be cleared before the
base metal surface dirt, grease, oxides, flame brazing should be a neutral flame, to avoid overheating of the base metal and burnt brittle. Welding the
workpiece 101, 102 or 103 silver solder powder and flux should be used as flux.
Silver copper and zinc tin co tin in can reduce the melting point of solder, to improve its liquidity. For example, the AgCuZnSn22-l7-5 series
alloys, the melting temperature is 620 ~ 650 ℃, the tensile strength of 294.2MPa elongation is 32%. Vickers hardness 1176.8MPa. The alloy can be
used for the induction furnace, it is better because of its scalability, it also can be processed into all kinds of wire and sheet. It is mainly in the nominal
exchange 125, 250 V or DC 31.5,250 V is used to manufacture the electronic components of electronic devices fuse.
Grades and performance of silver copper phosphorus environmental solder silver copper phosphorus brazing
HAg-2B (containing 2% silver) is equivalent to American Standard AWS Rem-6, the GB BCu91PAg and L209, with good fluidity and filling ability, widely
used in air conditioners, refrigerators, electrical and mechanical industries, copper and copper alloy brazing . Melting point of 645-790 degrees Celsius.
The HAg-5B (5% silver) is equivalent to American Standard AWS Rem-3 GB BCu88PAg and the L205, a certain plasticity, applicable to maintain close
co-joint welding of copper and its alloys. Melting point of 645-815 degrees Celsius.
The HAg-15B (15% silver) is equivalent to American Standard AWS Rem-5 GB BCu80AgP and the L204, with the connector plastic, electrical
conductivity to improve, especially for uneven gap occasions. Can be brazed to withstand the vibration load of brazed joints of copper and its alloys.
Melting point of 645-800 degrees Celsius.
Analysis of China s valve industry
At present, China\\ s valve market annually turnover of up to 500 billion yuan, of which the valve of more than 100 billion market
has been abroad, valve enterprise occupation. In accordance with
China\\ s \"Eleventh Five-Year\" development plan, China\\ s valve industry, especially in the valve business to focus on water supply
and building two major markets in the energy-saving, environmental
Compared with the international advanced enterprises are still gaps in the protection, security, sustainable development strategy.
It is understood that: Chinese enterprises to smaller, low technical level, the competitiveness of the brand is still
relatively weak. If these problems is less than
To be resolved, not only greatly affect China\\ s valve industry supporting the overall level, but also restricts the healthy growth
of China\\ s valve industry. Integration re-
The group is to go through the process of China\\ s valve industry. Only through large-scale, large-scale integration of high-
quality assets, the rapid formation of a strong group
Order for brands to become China\\ s valve market leader in order to ensure that the urgent needs of the Chinese users, high-end
products.
\"Eleventh Five-Year\" period, the forecast domestic demand for valves total of 34.5 billion yuan. In addition, according to the
needs of China\\ s national economic development, the valve
The focus of development of thermal power, nuclear power, hydropower, large-scale petrochemical, oil and natural gas gathering
pipelines, coal liquefaction and metallurgical and other major construction projects, supporting
Valve development of new products. In the development of new products at the same time, should pay attention to the promotion and
application of new technology, such as the development of high temperature and pressure stations and nuclear
Power station valve forge welding structure, application of vacuum electron beam welding of new processes and shear extrusion
technology; the development of long distance pipelines of large diameter as a whole ball valve application
Overall welding technology.
The valve is petroleum, chemical, power plants, long-distance pipelines, shipbuilding, nuclear industry, a variety of
cryogenic engineering, aerospace and marine oil and national economy
Various departments indispensable fluid control equipment.
After 20 years of development, various sizes valve business in China about 6,000 more than the number of firms in the world,
including the annual output value over 500
900 million. From a product point of view, the valve industry in China has been able to produce more than a dozen categories of
products, such as ball valve, butterfly valve,
Cut-off valve, safety valve, check valve, solenoid valve, piston valve, drain valve, angle seat valves, steam traps, emergency
shut-off valve.
The National Development and Reform Commission issued a Notice No. 11 of 2008, 351 new industry standard on July 1, 2008,
which the machinery industry standard 253
, Involving 30 of the valve industry. In support of national policies 2008-2009 valve industry will maintain a good momentum of
development. Forecast 2010
China Valves total sales of 6.736 billion yuan, the valve exports amounted to $ 2,009,000,000, the valve imports amounted to $
3,632,000,000
Pinch Valve (Tube by Pinch Valve):
Structure: the valve from the upper and lower aluminum alloy body, rubber tubing, the size of the stem gate, the upper and lower guide post and other parts.
How it works: when cis resale round, the size of the stem the same time promote Xiacha board compression sleeve to shut down the contrary that line open. In this way, the gate between the guide post up and down reciprocating completion of valve opening and closing work.
In the country also known as the pinch valve, hose valve.
Bing Qi Valve hose clamp valve products are as follows:
"GJ41X cast iron clip-34/">pipe clip valve" → "GJ41X aluminum alloy Pinch Valve →" GJ941X, electric hose clamp valve "→" GJ841X pneumatic tube clip valve "→" GJ6K41X normally open pneumatic Pinch Valve → "GJ6B41X normally closed pneumatic Pinch Valve "→" Austrian liner Pinch Valves
Valve material: cast iron, aluminum, cast steel; valve specifications: DN15-DN400; pressure: 1.0Mpa; drive mode: manual, electric, pneumatic; Standard: GB GB of.
Material to prepare parents should do for the newborn?
according to the different seasons, ready to summer or winter clothes, each of at least 2 to 3 sets of clothing should be selected soft and easy to absorbent cotton cloth or pure cotton. Newborns neck is short, T-shirt made of a monk collar “, do not attach the buttons to prevent the destruction of the skin of children. Pants can be made of sack with the pants, which will help pediatric feet warm. Cap, shoes, socks have to get ready, each with enough on the line, do not have time to buy too much. Full, diapers, use white or light-colored old cotton diapers and changing mat to prepare, before use with boiling water or hot, and then dried in the sun, to achieve the purpose of disinfection. Qualified families can be used disposable diapers and diapers changing mat.
Food: newborn to eat the breast milk the best, but also prepare baby bottles, pacifiers, milk pot, and wash and disinfect the bottle brush and steamer. Conditional also purchase fresh milk to the lack of breast milk or wet nurse sick children eating. Bottle to buy a glass bottle can easy cooking disinfection. Pacifier to prepare a few, once damaged can replenish. In addition, also buy some cod liver oil concentrate (vitamin AD drops) and calcium powder, prescribed to add to the newborn.
Live: the newborn is best to live in sunny, warm, noise, ventilation, good room. Indoor bulb light should not be too strong, so as not to stimulate the child. Select the crib should be economical, practical and safe. Small quilts, small clip, small packets of cloth (one meter square), small blanket, small pants, each 2 to 3 sets of cotton products best. The pillow of the newborn should not be too high, can be filled with millet or bean shell.
: Skin care products kk buy baby soap, baby bath, baby moisturizer, pine pollen (after washing the butt bashing with), powder (summer prepare prickly heat).
cutting Bag Making Machine Application and Features
Purposes and characteristics of the cutting Bag Making Machine
First, use:
Applicable to the production of clothing bag, socks bag, towel bag, bread bag, jewelry bag, lingerie bag, stationery bags,
electrical components, bags, bamboo wood products, bags and other plastic film bags.
Second, the processing of materials: BOPP, PP, PE, heat shrinkable film a variety of heat sealing materials.
Third, the performance characteristics:
1, the whole machine adopts microcomputer control, stepper motor to pull material (optional servo motor control system).
2, the computer fixed length, step photoelectric tracking, accurate, smooth, automatic shutdown of the label is lost, feeding
photoelectric control.
Automatic counting, count alarm, and set the whole downtime.
4, heat sealing lace; automatic punch (hanging hole, vent); automatically gum paste.
Chinese LED industry the soft underbelly of
In the upper reaches of the soft underbelly of China s LED industry
The world is the initial formation of the LED industry, the pattern of the three regions, Asia, North America, Europe, Japan s Nichia, Toyoda Gosei, USA Cree, Lumileds and Osram patented core technology competitive landscape. US-Japan epitaxial wafers,
chip technology, equipment with monopolistic advantages, highlight the advantages of European companies in the field of applied technology.
From 1999 to 2009, LED related patent applications in the United States in 3312, Japan ranked first, accounting for about 50 percent, the United States, accounting for 30% of Chinese Taiwan s third, is 11%.
LED industry chain mainly includes four parts: LED epitaxial wafer growth, wafer fabrication, device packaging, and product applications, in addition to the related industries.
LED epitaxial wafers and chips in the LED industry chain accounts for about 70% profit industry about 10-20% of LED packaging, LED applications probably accounted for 10-20%. Match is to gradually reduce the LED industry chain from upstream to
downstream industries, barriers to entry.
The substrate materials used to manufacture LED chips are usually high-quality sapphire or silicon carbide, GaAs (gallium arsenide), epitaxial growth of a variety of compound semiconductor crystal. At present, the growth of AlInGaP on GaAs is a relatively
mature technology, the next GaAs substrate will continue to be a reliable choice of substrate material. Sapphire substrate due to good performance in large-size substrates, as manufacturers continue their efforts to the development of large-size substrate
process will gradually take a larger proportion.
The growth of epitaxial wafers LED manufacturing technology, is commonly used by metal organic chemical vapor deposition (MOCVD) method. Current global MOCVD manufacturer AIXTRON company in Germany and the United States VEECO Company,
the former accounting for 60% -70% share of international markets, which account for 30% -40%, the Japanese NipponSanso production equipment is basically limited to domestic sales .
Is the pointer of the LED industry
Japan is the largest producer of global LED industry, accounting for 50% market share, their movements almost is a pointer of the LED industry. Revenue of the Chinese LED industry in Taiwan accounts for 17% of global revenues, second only to Japan,
ahead of South Korea, Europe and the United States. Taiwan is a global consumer electronics production base, the world s largest LED downstream packaging and middle reaches of the chip producer. Taiwan, China and the mainland are mainly focused on
the development of packaging and assembly aspects of production accounted for the world s first output value ranked second in the world.
The LED industry is rapidly becoming one of the most popular industry. Ten years later, the LED world. Sales output value of China s LED industry in 2009 amounted to 60 billion yuan, an adverse economic growth for more than 30 percent, making China
one of the global LED industry, one of the fastest growing region. China s LED market is currently in a major leap forward in the process from the order of magnitude ten billion to one hundred billion middleweight.
LED industry cake bigger fast
As an electrical energy into light of semiconductor devices, LEDs (light emitting diode) power consumption is only the incandescent lamp 1/10, energy-saving fluorescent lamps 1/3, life is 100 times that of incandescent lamps. Compared with conventional
light sources, LEDs do not use mercury, lead and likely to cause pollution elements, but also can be recycled, is a green light.
Ideas to build a low carbon economy of energy saving and environmental protection, China s LED industry cake is quick and bigger.
Relevant agencies, the LED lighting industry output value over 150 billion yuan in 2010, compared to 2008 doubled. Expected the fastest in 2015, the share of the LED lighting market in China will reach 20 percent, contributing to industrial scale up to 500
billion yuan, China will enter the top three global LED lighting market.
In October 2009, the National Development and Reform Commission, Ministry of Science and other six ministries jointly issued the "semiconductor lighting energy industry views a clear goal: to 2015, average annual growth rate of the semiconductor lighting
industry output about 30%; functional 20% of the lighting; significantly enhance the ability of independent innovation of enterprises, upstream chip-scale production enterprises 3-5; industrial concentration significantly increased. Own brands, the backbone
of the leading enterprises of the larger influence on the market about 10; achieve annual energy saving of 40 billion kwh, equivalent to 40 million tons of carbon dioxide emissions.