Main technical parameters for designing a new self-feed drilling machine

Abstract

The aim is to develop and substantiate a complex of technical and economic requirements for the design of a self-feed drilling machine produced in the Russian Federation, which is particularly relevant in the context of import substitution. The study considers self-feed drilling machines produced by Atlas Copco, Desoutter and Recoules as references to match their performance and specifications. By analogy with these machines, the limiting weight and overall dimensions of the developed machine should be up to 6 kg and 320x110x450 mm, respectively. The selection of motors for spindle rotation and axial feed is carried out by drilling a hole with a diameter of 12 mm in a mixed 58 mm thick stack using a carbide drill. This stack includes steel sheets (30KhGSA grade), polymer composite materials (carbon fibre-based), titanium alloy (Vt6 grade) and aluminium alloy (1933 grade). The required power for the electric drives was determined using cutting conditions specified in reference manuals and by drilling tests of a mixed stack carried out using a DMC 635 V machine equipped with a Kistler 9123CQ05 plate dynamometer. Oscillograms of axial force and torque showed that the highest resistance occurs when drilling the titanium alloy. The following specifications were calculated and confirmed for the projected self-feed drilling machine: the required power for the electric drives is 1.5 kW for the feed drive and 2.8 kW for the spindle rotation drive. The maximum required rotation speed is 1940 rpm, and the maximum required feed rate is 4.5 mm/rev. In order to grind chips and suppress potential auto-oscillations of the drill, it is recommended that the modulations of the feed and spindle rotation speeds created by a computer numerical control system be used. Future research will involve the production and testing of a prototype self-feed drilling machine, designed in accordance with the provided recommendations.