FJZJ-350-A High pressure hydraulic pipe expander

FJZJ-350-A High pressure hydraulic pipe expander

Brief introduction

High pressure hydraulic tube expansion machine is the second generation of hydraulic tube expansion machine developed by our company, mainly composed of hydraulic system, high pressure cylinder, high pressure hose, expansion gun, expansion rod, control box and other components. Especially in the deep hole expansion joint, it can be accurately positioned, and can also meet the different materials and different specifications of the pipe hole expansion joint. The expansion gun is light, easy to operate, suitable for single operation. After expansion, the pipe hole has no pollution, no residue, uniform expansion, and it also has the function of debugable forced pressure relief when the pipe hole is too small and the expansion rod is worn and difficult to pull out. In the production process to reduce losses, improve the comprehensive economic benefits.

Expansion pressure calculation

According to the actual conditions of the tube material and expansion geometry parameters, the expansion pressure can be calculated according to the following formula:

1、The residual contact stress of the pipe can be calculated by the following formula
　　Pc=(1-2C)Pi-σstlnkt(1)
　　其中C=1/{kt2(1-Ut)+1+Us+Et[(kt2-1)/Es(ks2-1)][1-Us+ks2(1+Us)]}

It can be seen from the above formula that when the pipe and pipe plate material and pipe hole structure size are fixed, C is a fixed value.

2、If f is the friction coefficient between the outer surface of the pipe and the hole of the tube plate, [q] is the allowable pulling force, and for the adhesive expansion [q]=2MPa and the strength expansion [q]=4MPa, the residual contact stress should meet Pc≥[q]/f(2).

By substituting the above formula into formula (1), it can be seen that the allowable value of expansion pressure should meet the following relation
　　[Pi]≥{[q]/f+σstlnkt}/(1-2c)(3)

3、The maximum expansion pressure is the pressure when the inner wall of the tube plate yields, that is:
　　Pimax=σstlnkt+σsplnks（4）

Therefore, the selection range of expansion pressure is
　　σstlnkt+σsplnks≥[Pi]≥{[q]/f+σstlnkt}/(1-2c)（5）

Symbol specification：

Es、Et—Elastic modulus of tube plate and tube material，MPa；
　　σsp、σst—Yield stress of tubesheet and pipe material，MPa；
　　Us、Ut—Poisson's ratio of tube plate and tube material；
　　C—Material and structural coefficients of tubes and tubesheet；
　　kt、ks Diameter ratio of single tube model of tube and tube plate，kt=do/di、ks=Do/Di；
　

When the special specification heat exchange tube is used, the appropriate pressure range of the expansion and strength expansion can be confirmed by theoretical calculation and simulation test to ensure the reliability of the expansion joint.

 Technical parameter