The key part of the system software is the stepper motor control software. The design method is described below.
1. Acceleration and deceleration software design
1) Determine the operating frequency
According to the maximum processing capacity of band saw. The required torque of the lead screw is calculated and the stepper motor which meets the requirement of the torque is selected. The static torque index of power stepping motor is relatively high, and it can be directly loaded. According to the operating moment-frequency characteristics of the selected stepping motor, a reasonable maximum output frequency, i.e. operating frequency, is determined. The higher the maximum output frequency is, the greater the torque loss will affect the load capacity of the stepping motor; if the operating frequency is low, the efficiency of the bandsaw will be affected.
2) Determine the starting frequency
Starting frequency, also known as sudden jump frequency, refers to the highest pulse frequency that stepping motor can start without losing step. Since the bandsaw starts with a load when using the stepper motor, the no-load starting frequency (maximum starting frequency) given in the product index can only be used as a reference. Load starting frequency is related to load torque and inertia. The starting frequency is determined according to the relationship between the maximum starting frequency and the maximum starting frequency of the selected stepping motor and the load torque and inertia.
3) Selection of frequency-up time
Generally, the frequency-up time is set at 0.1-1 s, and the system takes 0.75 first. In order to prevent the stepper motor from losing synchronization when the frequency changes, the time of rising and falling frequency can be divided into several sections, and the frequency can remain unchanged in each period of time, so as to increase the reliability.
4) Measures to Change the Speed of Stepper Motor
The general practice is to change the timing time of internal or external timers, or to change the delay of software. This system considers not only reducing hardware circuit, preventing interference, but also occupying less time, and preventing interference caused by interpolation delay, so it chooses 8031 internal timer TO timing interrupt mode.