Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
781659 | International Journal of Machine Tools and Manufacture | 2013 | 8 Pages |
The temperature at the bottom surface of a hole being drilled is measured by using an infrared-radiation pyrometer equipped with two optical fibers. One of the optical fibers is inserted into the oil hole of an internal coolant carbide drill and passes through the machine-tool spindle. This optical fiber is connected to another optical fiber at the end of the spindle. Infrared rays radiating from the bottom surface of the hole being drilled are accepted and transmitted to the pyrometer by the two optical fibers. Temperature increases as drilling progresses, and it increases considerably near the bottom surface of the workpiece. In case of a 10-mm-thick carbon–steel workpiece, temperature reaches 190, 250, and 340 °C at drilling depths of 6, 8, and 10 mm, respectively. To investigate the effect of the increase in temperature on drill wear, a series of 10-mm-deep blind holes are drilled in workpieces with thicknesses of 10 and 25 mm. Tool wear is greater when the drill cuts a hole at the bottom of a 10-mm workpiece than that when the drill cuts a hole at the mid-depth of a 25-mm workpiece. This indicates that the rapid increase in temperature near the bottom of the workpiece effects the progress of drill wear.
► Temperature variation at the bottom surface of a hole being drilled was measured. ► A newly developed infrared-radiation pyrometer with two optical fibers was used. ► Temperature increased as drilling progressed. ► Temperature increased rapidly near the bottom surface of the workpiece. ► Temperature rise affected the progress of drill wear.