Contouring Head Basics

Know how contouring boring heads work? If not, here’s a quick explanation.


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East Texas Machine Works uses a number of Cogsdill ZX contouring heads on its horizontal boring mills. Although these heads can perform a number of machining operations in one setup, they function in a straightforward manner, says Don Aycock, Cogsdill ZX product manager.
Contouring heads transform a horizontal boring mill’s W-axis quill motion into radial cutting edge motion, Mr. Aycock explains. Inside each tool is an actuator shaft with an inclined key that precisely mates with a slot in a tool slide. Quill extension pushes the actuator shaft and causes the tool slide to move outward, increasing the diameter of the rotating cutting edge. Quill retraction decreases the cutting diameter.
Combining a machine’s quill motion with its table feed enables a single head to perform many operations. Facing can be performed by moving the quill (and thus, the cutting edge) while the machine’s table remains stationary. Keeping the quill stationary and moving the table enables boring and turning operations. Combined quill and table movements can generate features such as radii, chamfers, tapers and complex ID or OD contours.
Programming a contouring head is simply a matter of coordinating the machine’s W and Z axes to guide the cutting edge. Depending on the contouring head model, though, the ratio of quill stroke to radial cutting edge stroke might not be 1:1, and this must considered when creating part programs. For example, some ZX heads have a 2:1 ratio of quill stroke to cutting edge stroke.

Machine-specific bonnets enable a single head to be used across a variety of boring mill brands. The bonnet bolts to a mill’s outer spindle (the outer spindle provides the rotation for the cutter). The contouring head quickly installs into the bonnet and is secured via locking cam pins. Other ZX heads, including modular boring tools and valve seat tools, can also be installed on a mill’s bonnet.