A pipe flaring tool has two parts, a set of bars with holes that match the diameter of the pipe end to be shaped, and a yoke that drives a cone into the mouth of the tube.
The two most common shapes are a single flare, for pipes carrying low pressures like a fuel line,
and the double flare for higher pressures such as in a brake system.
To make a single flare, the pipe level is placed into the anvil level with the top of the flaring bars. With the clamp screw firmly tightened, the feed screw flares the end of the tube. Making a double flare is similar, but more of the tube is exposed to allow for the folding over into a double flare. A double flaring button is placed into the end of the tube, and when it is removed after tightening, the pipe looks like the the above image. Turning the feed screw completes the forming of the double flare.
A pipe cutter is more convenient and neater than a saw when cutting pipes and metal tubing.
The sharpened wheel does the cutting. As the tool turns around the pipe the screw increases the pressure, driving the wheel deeper and deeper through the pipe until it finally cuts right through.
There is also larger version that’s used for cutting exhaust pipes.