Page 239 - Demo

237DEEP HOLE DRILLINGMethod of Ejector System DTSThe ejector deep hole drilling system or double pipe system (DTS) is a system in which high pressure coolant is supplied to the machine spindle directly or through a connection adapter between the drilling tool and the machine (Figure 6.7.1.1).The drilling tool consists of an outer tube and an inner tube that are connected to a high-pressure coolant supply on one side and to the drill head on the other side. High pressure coolant is supplied through the annular gap between the outer and inner pipe of the tool to the drill head. Most of the coolant flow is directed through the coolant outlets around the circumference of the tool to the cutting edges of the drill head, allowing chips to be evacuated through the inner tube to the chip receiver. A small part of the coolant is fed directly into the inner tube via a sloped slot in the inner tube, thereby creating an ejector effect. The coolant flow coming out of the slots is directed along the inner pipe hole axis to its outlet end and sucks in the swarf from the cutting area, thereby improving the conditions for chip removal. This system requires less coolant pressure than the single tube system (STS) and can be successfully used on existing machining centers without significant changes.Figure 6.7.1.1workpiece material drill head outer tubeinner tubedouble tube connectormachinepilot hole stopper