碳弧气刨主要应用范围有哪些？
参考答案：
应用范围：
（1）主要用于双面焊时，清除背面焊根。
（2）返修焊件时，可使用碳弧气刨清除焊缝中的缺陷。
（3）利用碳弧气刨加工坡口，尤其是U型坡口。自动碳弧气刨用来为较长的焊缝和环焊缝加工坡口；手工碳弧气刨用来为单件、不规则的焊缝加工坡口。
（4）清除铸件的毛边、飞刺、浇冒口和铸件中的缺陷。
（5）切割高合金钢、铝、铜及其合金等。
Celebrating sleep World Sleep Day, observed on 21 March, was created to bring attention to the growing number of sleep problems worldwide. Sleep is a natural part of human life, but many people in the modern world ignore its importance. As a result, sleep problems are increasingly common. In 2002, scientists at the University of Athens in Greece conducted a survey of over 35,000 people in 10 countries around the world, including China, Belgium and South Africa. Of the people that responded to the survey, 24 percent said that they did not sleep well, and based on their responses, 31.6 percent were diagnosed (诊断)with insomnia（失眠）and another 17.5 percent were diagnosed with borderline insomnia. In addition, 30.7 percent of survey respondents reported visiting a doctor for help with sleep problems and 11.6 percent said that they felt very sleepy during the day. Overall, the survey found that ninny people suffer the effects of poor quality sleep, some examples of which are being unable to fall asleep and waking up in the middle of the night. The main factors causing these problems are pressure from school or work and a fast pace of life, but noise pollution and light pollution also interfere with sleep and contribute to poor quality sleep. The survey’s findings are particularly troubling because large numbers of people were found to have difficulty sleeping at night. The short-term effects of this are tiredness and trouble concentrating. If this happens for a long time, the risk of putting on weight and having a heart attack may increase. There are many things you can do to improve the quality of your sleep. First, you should have regular sleep habits. Try to go to bed and wake up around the same time each day. You also need to make your bedroom a cool, dark, quiet place to sleep so that heat, light and noise do not disturb you. At night, you should also avoid things that contain caffeine, such as chocolate, coffee, tea and many soft drinks, as caffeine may keep you from sleeping. Getting a good night’s sleep is important for everyone. By following the advice above, you can rest better at night and work better during the day. Title: Celebrating Sleep
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