问题 问答题 简答题

在锻造天车的操作中如何将钢锭端部插入平衡杆?

答案

参考答案:

钢锭浇口杯端成圆柱形后,由水压机的砧子压住钢锭的中间部分,这时锻造天车装上平衡杆,调整主、副钩,使平衡杆的锥孔对准钢锭的圆柱形端部,开动大车,使圆柱形端部插入平衡杆的椎孔内,但不能全部进入。点动大车,使平衡杆对钢锭产生一轴向力,同时开动转料机,带动平衡杆旋转,使钢锭圆柱形端部全部插入平衡杆的孔中。调整好大车位置,使平衡杆不再有推动钢锭的轴向力。钢锭的圆柱端插入平衡杆后,随着水压机的锻压,钢锭直径逐渐变细,而长度逐渐变长。此时要随时调节主、副钩的高度,使钢锭处于水平状态,防止主钩稍高,这样会使塔形弹簧压缩超载。

解答题
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C

In 1879, a group of explorers made an incredible find. They discovered paintings of remarkable beauty on the walls of a cave in Spain. Some scientists believed that these paintings were created by early humans from the Stone Age, between ten and thirty thousand years ago. Other scientists and the public did not believe the claim, but over the years, it was proven correct. Our ancestors had incredible artistic talents.

Most of the cave art that has been discovered has been found in Spain and France. A smaller number of such caves are located in Italy, Portugal, Russia, and other countries. Scientists believe that many more caves will be discovered in the coming years, and are concentrating their efforts on Africa and the area between Europe and Asia. These two regions of the world were, populated first by humans.

Cave art was carved or painted on the walls and roofs of caves, usually near the entrance. The entrance area was probably chosen to take advantage of daylight and to allow many people to view the paintings. In some cases, the art appears much deeper in caves and requires artificial light. Evidence suggests that the artists used torches or shallow bowls in which animal fat was burned.

9.What was the response of general public to the discovery of cave art made by Stone Age people?

A. They believed it at first.

B. They did not believe it.

C. They thought it was beautiful.

D. They ignored it.

10.According to the passage, what can we conclude about animal fat?

A. It does not burn.

B. Stone Age artists used it to preserve their paintings.

C. It can be burned to produce light.

D. Stone Age artists mixed it with their food.

11.. Where do scientists expect to find more cave paintings?

A. In Central and South America.

B. In Spain and France.

C. In the places where there are caves with large openings.

D. In the regions of the world first populated by humans.

12.Where would this passage be most likely to appear?

A. In a textbook about early human history.

B. In a textbook about modern art.

C. In a dictionary.

D. In an encyclopedia entry about caves.