Automation of Heat Exchanger Shell Holes Machining Operation

The design of the shell and tube heat exchanger includes a tubelike shell with holes to which an inlet and outlet pipes are welded. Radial and tangential holes are produced manually by means of plasma cutting with the use of specialized tools, which determines high laboriousness of heat exchanger production. An automatic device is proposed to reduce the laboriousness of this operation. To produce the hole in the heat exchanger shell, two reversible motions are superimposed: linear motion of the cutter along the longitudinal axis of the shell and the shell rotary motion. A mathematical model of the required cutter motion is proposed, which describes the relative trajectories of the plasma cutter and the shell in parametric form. To verify theoretical premises, a prototype of the device was produced using a 3D prototyping technology, a ball screw for the reversible linear motion of the cutter and a stepper motor for the reversible rotary motion of the shell. The shell is fixed by means of a collet chuck and rests on the pipe roller support. The principles of automatic control of the linear and rotary motions of the cutter and the shell are proposed, based on the 3D model of the shell.