Question

A CNC worktable is driven in a linear direction by a lead screw connected directly to a stepper motor. The pitch of the lead screw is 5 mm. The stepper motor completes one full revolution upon receiving 600 pulses. If the worktable speed is 5 m/minute and there is no missed pulse, then the pulse rate being received by the stepper motor is

• A. 20 kHz
• B. 10 kHz
• C. 3 kHz
• D. 15 kHz

Hint:

For stepper motors, the pulse rate can be determined by calculating the number of pulses needed to achieve the desired speed of the worktable. Ensure to convert units properly when dealing with time and distance.

Answer 1

The Correct Option is B

The lead screw has a pitch of 5 mm, meaning each revolution of the screw moves the worktable by 5 mm. The stepper motor receives 600 pulses for each full revolution, so it moves the worktable by \( \frac{5}{600} \) mm per pulse. We are given that the worktable moves at a speed of 5 m/min, or 5000 mm/min. To find the pulse rate, we need to calculate how many pulses the motor receives per minute: \[ \text{Pulses per minute} = \frac{5000 \, \text{mm/min}}{\frac{5 \, \text{mm}}{600 \, \text{pulses}}} = 600 \times 1000 = 600000 \, \text{pulses/min}. \] Now, convert the pulses per minute to pulses per second (Hz): \[ \text{Pulse rate} = \frac{600000 \, \text{pulses/min}}{60} = 10000 \, \text{pulses/second} = 10 \, \text{kHz}. \] Thus, the pulse rate is 10 kHz, and the correct answer is (B).