| 摘要 |
The present invention relates to a tool and a means for the replacement of underground ducts. The tool being in principal self-propelling consists of a breaking part (25) and a pipe connection part (24). The tool is hydraulically operated over hydraulic tubes (7). The breaking part (25) has break segments (1) with stepwise increasing radius and the pipe connection part (24) has a feeding cylinder (14). One or several double pistons (2) are attached to the segments (1) by lifting links (4). Each double piston (2) moves in two cylinders (9, 10), which are so connected that when the pressure acts on the piston rod side in one of the cylinders then the pressure in the other cylinder acts on the side without piston rod and vice versa. The lining with new pipes (16) takes place according to the operating cycle below. The breaking part (25) is first expanded radially outwards, whereby the existing pipe is restored to a circular cross section or is expanded to a larger diameter. Then the feeding cylinder will advance the new pipe (16). At this moment a wire (8) acts as an extra counter force in order to assist the tool, which is expanded against the existing pipe. When the new pipe (16) has been advanced the breaking segments will return, whereby the diameter of the tool is decreased, and then the tool is advanced. This ends the operating cycle and, thus, the next step will be to expand the tool radially. |
