INCREASING THREAD CUTTING PRODUCTIVITY WITH A COMBINED TOOL

The article discusses increasing the productivity of thread cutting on a CNC lathe using a combined tool – a comb-type cutter. The tool consists of several consecutively arranged cutting teeth that provide sequential boring and thread cutting, combining roughing and finishing operations in a single pass. Experimental studies were carried out on St20 steel blanks with a diameter of 30 mm. The cutting speed ranged from 40 to 70 m/min, the feed from 0.12 to 0.18 mm/rpm. At the same time, the thread processing time was reduced from 60 seconds (traditional chisel) to 32 seconds (comb cutter). The wear of the cutting edges under optimal conditions was 0.18 mm, which is 28 % less than with a classic tool. The quality of the thread profile corresponds to GOST 24705-81 with a surface roughness of no more than Ra 1.6 microns. The comb cutter reduces vibrations and ensures uniform load distribution between the teeth, which increases tool life and processing stability. The recommended optimal modes are a speed of 60 m/min, a feed of 0.15 mm/rpm. This technology makes it possible to increase threading productivity by 40–47 %, reduce cost and increase tool life, which makes it promising for mass production. Keywords: comb cutter, threading, combined tool, productivity, cutting modes, tool wear, thread quality, metalworking.