Project ForgeManufacturing Engineering
Machining Processes
GATE 2008
Medium
In the feed drive of a point-to-point open loop CNC drive, a stepper motor rotating at 200 steps/rev drives a table through a gear box (gear ratio U=1/4) and a lead screw-nut mechanism (pitch=4mm, number of starts=1). The stepper motor executes 1 step/pulse of the pulse generator. The Basic Length Unit (BLU), i.e. the table movement per pulse of the pulse generator, is
- A0.5 microns
- 5 microns
- C50 microns
- D500 microns
Explanation
One motor revolution = 200 pulses/steps, producing lead-screw rotation = U×1 rev = 1/4 rev at the table's screw, giving table travel = pitch×U=4×(1/4)=1mm per motor rev. BLU=1mm/200 pulses=0.005mm=5 microns.
Source: GATE ME 2008 (2008)
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