There are several ways to open the anti-smashing device of the cotton machine, most of which is realized by hardware circuits. This method has the disadvantages of being difficult to maintain and the control accuracy is not high. This paper introduces an anti-smashing device realized by Siemens S7-200PLC software.

The biggest feature of the device is that when the cotton opener has a tendency to brake, the cotton motor is stopped to feed the cotton according to the speed of the hand shaft, and the speed of the reduction can be set. The working principle is as follows:

A non-metallic disc is mounted on the hand shaft with a small piece of metal. As the disc rotates with the hand axis, the metal block passes over the proximity switch and the proximity switch outputs +24V, creating a rising edge. When the metal block leaves the proximity switch, the proximity switch outputs 0V, producing a falling edge. As the beater shaft rotates, the proximity switch outputs a series of pulses. From the falling edge of one pulse to the falling edge of another adjacent pulse, this time is the time it takes for the hand axis to rotate one revolution. The time of the hand axis can be obtained by measuring this time.

When I0.0 is raised from a high level to a low level, the off-delay timer T32 counts from 0. When the rising edge of I0.0 is changed from low level to high level, the value of T32 is sent to the variable memory VW0. At this time, T32 is still counting, that is, the condition of T32>VW0 is established, and the value of T32 is sent to the variable memory VW2. When I0.0 turns from high level to low level, the hand axis rotates exactly one week. The value in VW2 is the time used for the hand axis to rotate one week. The unit is ms. T32 restarts counting from 0, the condition of T32>VW0 is not established, the value of T32 cannot be transmitted to VW2, and VW2 still maintains the value before the falling edge. This value is the time taken for the hand axis to rotate one week. At this time T32

In the event of a brake phenomenon, if the speed of the hitch shaft is reduced to 15r/s to stop the cotton feed to the cotton, then in the program, the comparison command is used to make the actual speed of the beater shaft VW4 and the set stop feed speed 15r/ s comparison. If VW4 is less than 15r/s, the inequality is established. After the delay delay timer T37 is delayed by 2s, the PLC digital output terminal Q0.0 outputs a high level relay J to pull the cotton motor to stop the cotton feeding, thus avoiding The phenomenon that the opener was drowned. When the speed of the beater shaft returns to normal, the inequality does not set up the relay J to release, and the cotton motor is automatically supplied with cotton. The delay of 2 s causes the relay J to pull in, in order to prevent the frequent operation of the relay J when the speed changes around the set value.

The device is not only suitable for the opener but also for the equipment with speed control requirements such as a carding machine, and one S7-200 PLC can control multiple devices, and the cost is low and practical, and maintenance-free.