问题 问答题 简答题

压延过程中锟筒分离力对压延制品和压延操作有什么影响?从降低分离力角度看,在制备压延设备以及压延操作中应采取和注意哪些因素?

答案

参考答案:

分离力:在压延过程中,锟筒对物料施加压力,而物料对锟筒产生反作用力这个使锟筒趋向分离的力叫分离力。分离力的作用会使锟筒产生弯曲变形使压延制品中间厚两边薄。采取的措施注意问题:1.锟距:锟距与下成反比关系,生产很薄制品时,分离力会很大,一般压延不适合太薄制品。2.物料粘度越大,分离力越大。3.实际测量的结果表明锟筒速度增加分离力也增加,但增加速度不明显。4.随锟筒直径和长度增加,分离力成线形增大,这就是即使在控制长径比较好的情况下,仍不能无限增大锟筒尺寸的原因。5.锟筒进料处在料量越多,钳径区面积越大,锟筒分离力越大。6.如果供给压延机物料呈片状或条状,则加料连续均匀,对锟筒的冲击作用小,锟筒分离力波动也小,如果供给压延机物料呈块状,进料间歇不均匀,对锟筒冲击作用大,分离力波动也大

阅读理解

阅读表达。

     A LONG time ago, there was a big apple tree. A little boy liked playing around it every day.

     As the little boy grew up, he no longer played around the tree.? One day the boy came back to the

  tree. He looked sad.

     "What's troubling you?" asked the tree.

     The boy replied (回答): "I want my own house. I need money to buy it."

     "You can pick my apples and sell them. Then you will have money."

     The boy was so excited. He picked all the apples on the tree and left happily.

     A few years later, the boy returned. He told the tree that he wanted to go sailing around the world."Use

  my branches (树干) to build your boat. You can sail far and be happy." So the boy cut the tree branch to

  make a boat. He went sailing and didn't return for a long, long time.

     Many years later, the boy returned. "Sorry, but I don't have anything for you anymore," the tree said,

 crying.

     "All I need is a place to rest. I am tired after my travels."

     The tree replied: "Good! Old tree roots are the best place to rest." The boy sat down and the tree was

  glad.

     The tree in this story is like your parents. Your parents are stable (可靠的) and giving, like a tree, and

  will always love you, no matter where you are.?

     Key words:   trouble v. 麻烦   return v. 回来,归还    sail v. 航海

1. Did the boy play around the big tree when he grew up?

    ___________________________________.

2. How did the boy get the money?

    ___________________________________.

3. What did the boy use the branches for?

    ___________________________________.

4. How did the boy feel the last time he returned to the tree?

    ___________________________________.

5. What does the writer compare (比作) the tree to?

    ___________________________________.

问答题 简答题