In the present work, the microstructures of A356 feedstock cast via a pipe consisting of partial inclined and partial vertical sections were investigated. The experimental results indicate that semisolid feedstock wit...In the present work, the microstructures of A356 feedstock cast via a pipe consisting of partial inclined and partial vertical sections were investigated. The experimental results indicate that semisolid feedstock with ideal microstructures can be obtained at higher temperatures 645℃ and above by the proposed process, and the solid shell inside the pipe can be avoided at the optimum pouring temperature. Thus the process is attractive for industrial applications. The slanted angle of inclined section has an influence on the optimum pouring temperature. That is, the bigger the slanted angle, the higher the optimum pouring temperature, but accordingly, the greater the possibility of solid shell occurring inside the pipe. Therefore, small slanted angle should be considered first on the premise of ensuring a certain nucleation. The formation of semisolid feedstock is owed to the coactions of wall nucleation and stirring resulting from fluid flow. The inclined section greatly affects nucleation, and the vertical section has an important effect on both nucleation and generating stirring.展开更多
The PE-Al-PE composite pipe is a multiplayer pipe t hat is composed of PE (polyethylene) and Aluminum. Al is inlayed the inner PE la yer and the outer PE layer. In the producing technological process of this kind of p...The PE-Al-PE composite pipe is a multiplayer pipe t hat is composed of PE (polyethylene) and Aluminum. Al is inlayed the inner PE la yer and the outer PE layer. In the producing technological process of this kind of pipe the bend forming of Al belt to tube is very important. It is the bend fo rming dies that are used in the process of producing PE-Al-PE pipe that is stu died in this article. To make a elaborate division, these dies can be classified as bending dies and forming dies here. In this paper, the designation of bendin g dies and forming dies that are used in producing technological process of PE- Al-PE pipe is put forward. The process starts from a coil of Al belt, in the ac tion of pulling force, passes between several bending dies to change its shape. The first step is to change Al belt to U shape. A couple of rolling wheels can b e used to shape the Al belt. The Al belt goes between the two rolling wheels, dr ives the wheels, at the same time is formed as the shape of the rolling wheels. Considering of the factors such as spring of the bend Al belt, frictional force between Al and the die, bending force needed to bend Al belt, etc., it must be s haped gradually into U by several dies. The designation of these dies has been g iven in this paper. The next step is to forming the U shape into a circle. The U shape Al belt goes through a round that is formed with a four-roller die, and then is shaped to a circle. Because the latter procedure requires the Al circle has a laminated area to be ultrasonic welded, this die must be designed to let t he two edges of the circle belt to be piled up to a definite width. But except f or the laminated area the other of the circle should be as round as possible. So the four rollers are not the same. The calculation and designation of the rolle rs of this four-roller die has also been given. The designation of the roller w hich is supposed to leave a gap to let the two edges of the circle belt to be pi led up is to make a fine rotation of an original circle. Then calculates the cen ter of the rotated arc and defines the arc completely. The designation method of the other rollers has also been given in this paper.展开更多
基金supported by the National KeyBasic Research Foundation of China under grant No.2006CB605203the National Hi-Tech Research Founda-tion of China under grant No. 2006AA03Z115 the National Natural Science Foundation of China under grantNo.50774007.
文摘In the present work, the microstructures of A356 feedstock cast via a pipe consisting of partial inclined and partial vertical sections were investigated. The experimental results indicate that semisolid feedstock with ideal microstructures can be obtained at higher temperatures 645℃ and above by the proposed process, and the solid shell inside the pipe can be avoided at the optimum pouring temperature. Thus the process is attractive for industrial applications. The slanted angle of inclined section has an influence on the optimum pouring temperature. That is, the bigger the slanted angle, the higher the optimum pouring temperature, but accordingly, the greater the possibility of solid shell occurring inside the pipe. Therefore, small slanted angle should be considered first on the premise of ensuring a certain nucleation. The formation of semisolid feedstock is owed to the coactions of wall nucleation and stirring resulting from fluid flow. The inclined section greatly affects nucleation, and the vertical section has an important effect on both nucleation and generating stirring.
文摘The PE-Al-PE composite pipe is a multiplayer pipe t hat is composed of PE (polyethylene) and Aluminum. Al is inlayed the inner PE la yer and the outer PE layer. In the producing technological process of this kind of pipe the bend forming of Al belt to tube is very important. It is the bend fo rming dies that are used in the process of producing PE-Al-PE pipe that is stu died in this article. To make a elaborate division, these dies can be classified as bending dies and forming dies here. In this paper, the designation of bendin g dies and forming dies that are used in producing technological process of PE- Al-PE pipe is put forward. The process starts from a coil of Al belt, in the ac tion of pulling force, passes between several bending dies to change its shape. The first step is to change Al belt to U shape. A couple of rolling wheels can b e used to shape the Al belt. The Al belt goes between the two rolling wheels, dr ives the wheels, at the same time is formed as the shape of the rolling wheels. Considering of the factors such as spring of the bend Al belt, frictional force between Al and the die, bending force needed to bend Al belt, etc., it must be s haped gradually into U by several dies. The designation of these dies has been g iven in this paper. The next step is to forming the U shape into a circle. The U shape Al belt goes through a round that is formed with a four-roller die, and then is shaped to a circle. Because the latter procedure requires the Al circle has a laminated area to be ultrasonic welded, this die must be designed to let t he two edges of the circle belt to be piled up to a definite width. But except f or the laminated area the other of the circle should be as round as possible. So the four rollers are not the same. The calculation and designation of the rolle rs of this four-roller die has also been given. The designation of the roller w hich is supposed to leave a gap to let the two edges of the circle belt to be pi led up is to make a fine rotation of an original circle. Then calculates the cen ter of the rotated arc and defines the arc completely. The designation method of the other rollers has also been given in this paper.
