Roller expansion method is to embed three small-diameter rollers on one frame, and a cone-shaped mandrel expander in the middle. When expanding the tube, insert the cylindrical part of the expander into the tube hole, using electric and wind. The equal power rotates the mandrel, and the roller rotates circumferentially along the mandrel, so that the mandrel is squeezed into the inner surface of the tube and the tube is forced to expand, so as to achieve a certain degree of expansion, so that the tube is tightly engaged with the hole of the tube sheet.
The expansion tube operation can be divided into two types: forward type and backward type. The advance type is to insert the frame into the tube, rotate the mandrel, and advance the extrusion. After reaching the specified degree of fastening, the motor is reversed, and the tube is pulled out to complete the tube expansion process. .
The reverse type and the forward type rotate the mandrel forward. When the original tightening degree is reached, the motor stops, and the clutch engagement of the reverse device reverses. The relative position of the roller and the mandrel remains unchanged. The parallel expansion tube is continuously and uniformly performed at a depth to the inlet. Since the expansion process is from the inside to the outside, the elongation of the tube occurs outside the tube sheet, which can eliminate the stress state of the tube bundle and improve the product quality, so it is used for the connection of the expansion length of more than 60 cm.
Explosive tube expansion process is to use high-energy explosives to make the shock wave generated by the explosion at the moment of the explosion, forcing the tube to produce high-speed plastic deformation, thereby expanding the tube and tube plate together to achieve the connection between the tube and the tube sheet.