There are several ways to prevent the choke of the cotton opener, most of which are realized by hardware circuits. This method has the disadvantages of being difficult to maintain and low in control accuracy. This article introduces a kind of anti-cheeping device realized by Siemens S7-200PLC software.

The biggest feature of the device is that when the cotton opener has a tendency to choke, the cotton feeding motor is stopped according to the speed of the beater shaft. This reduction speed can be set. Its working principle is as follows:

A non-metal disc is installed on the beater shaft, and a small piece of metal is set on the disc. When the disc rotates with the beater shaft, the metal block passes above the proximity switch, and the proximity switch outputs + 24V, which generates 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 beater shaft to make one revolution. The speed of the beater shaft can be obtained by measuring this time.

When I0.0 changes from high level to low level to generate a rising edge, the off-delay timer T32 starts counting from 0.When I0.0 changes from low level to high level to generate a rising edge, the value of T32 is sent to the variable memory VW0.At this time, T32 is still counting, that is, the condition of T32 & gt; vw0 is true, and the value of T32 is sent to variable memory vw2. When I0.0 When the falling edge is generated from the high level to the low level, the beater shaft just rotates for one cycle. The value in vw2 is the time taken for the beater shaft to rotate for one cycle, in Ms. at this time, the disconnection delay timer T32 starts counting from 0 again, T32 & gt; The vw0 condition is not tenable, the T32 value cannot be transmitted to vw2, and vw2 still keeps the value before the arrival of the falling edge, which is the time taken for the beater axis to rotate for one week.

When there is a choke phenomenon, if you want to reduce the speed of the beater shaft to 15r / s to stop the cotton feeding motor, then use the comparison command in the program to make the actual speed of the beater shaft VW4 and the set stop feeding speed 15r / s comparison. If VW4 is less than 15r / s, the inequality is established. After a delay of 2s after the on-delay timer T37, the PLC digital output Q0.0 outputs a high-level relay J, which causes the cotton feeding motor to stop feeding, thus avoiding In order to choke on the opening machine. When the speed of the beater shaft returns to normal, the inequality is not established, the relay J is released, and the cotton feeding motor automatically feeds the cotton. The delay 2s causes the relay J to pull in to prevent frequent operation of the relay J when the speed changes around the set value.

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