Butterfly valve, as one of the main types of the prosperous valves, has been widely used in many fields. It is mainly applied to achieve piping on-and-off and flow control. Generally speaking, it has been popular in the fields of the petroleum, chemical industry, metallurgy, electricity and water and so on. With the increasing requirements and complex working conditions, it is not enough to just use the existing materials to form the fixed structure which is restricted for the applications of high temperature, high pressure, strong corrosion or strong abrasion. Fortunately, there are some new specified types which are expected to carry the unpleasant situation out.

At present, there is a kind of butterfly valve which is called triple eccentric multiplex ring metal-seat butterfly valve. It is a new valve which has greatly made good use of the advanced technologies. The valve body and the valve seat is one piece. And it is the hard sealing whose face is around with the materials with resistance to high temperature and strong corrosion. The specially defined structure aims to make the operation be convenient and smooth, together with the better tightness. However, as a new invention, there are still a lot of points which need improvement.

It appears that the multi-layer stacked rings are fixed to the valve plate. When the valve plate is within the normally open state, the medium would directly flow to the sealing face. Within the long period of erosion, the soft ring would be damaged more or less, leading seriously to the failure of the tightness. Then, it is not admitted to produce the diameter of DN200, resulting from the thick overall structure. What else, as the sealing is on the transmission of torque pressure to pass the power from the valve plate to the valve seat, the countercurrent flow of the medium would increase the pressure, leading the damage to the sealing. Since there are still plenty of problems needed to be solved, the competent advantages and outstanding performance should not be ignored. Generally speaking, the new type can be use as a gate vale, a stop valve or ball valve. No matter what, after a period, it would be bring in more and more benefits.

A ball screw is a mechanical device on which the ball can exercise between the nut and the screw. Besides, it can translate the rotational motion to linear motion with little friction. It has many characteristics such as high precision, long life, and low pollution. Moreover, it can reverse the drive at high speed. Due to its specific features, ball screw is becoming one of the important components used in the precision machinery industries, positioning and measurement systems.

The application of it does not have a very long history. Traditional screw was very poor in positioning and was quite easy to be damaged. Not until 1898 that people first tried to put the steel ball between nut and screw to replace the sliding friction with the rotational friction so as to improve the bad position. In 1949, a ball screw device was placed in the car and it became a great revolution in the application of the ball screw. Gradually, the traditional screw (ACME) was replaced. And in recent years, it becomes one of the components that are widely used in the industries.

Originally, only the United Kingdom, the United States, Germany, Japan and other advanced industrial countries can produce these products with a large quantity. Since 1982, He Feng Precision Company had set up factories to manufacture this product. And with the quick development, the research and development ability of ball screws can compete with advanced industrial countries. These products are mainly formed by screw, nut, ball, holder, wipers, and the return tube. The ball assembly acts as the nut while the threaded shaft is the screw. Due to their different circulatory systems, they can be divided into different kinds such as ball screws with outside circular and internal circulation, etc.

This mechanical component has a wide range of usage. It can be widely used in industrial machinery such as precision machine tools, industrial machinery, electronic machinery, and transport machinery, etc. Ball screws are used in aircraft and missiles to move control surfaces, especially for electric fly by wire. They are also used in machine tools, robots and precision assembly equipment. In addition to the above applications, it can also be applied in the drive of the computer disk drive starter, the adjustment of the aircraft wings, and medical X-ray examination. All in all, it plays a rather important part in the development of different industries. And it is quite necessary to learn something about this mechanical device.