Release Time：2018-07-26 Information Sources：Rongda Browse：
There are several ways to prevent the choking device of cotton opener. Most of them are implemented by hardware circuit. This method has the disadvantages of not easy maintenance and low control accuracy. This article introduces a kind of anti choking device realized by SIEMENS S7 - 200PLC software.
The biggest characteristic of this device is that when there is a choking tendency in the cotton machine, the cotton feeding motor is decided to stop feeding according to the speed of the beater axle. This speed can be set. Its working principle is as follows:
A nonmetal disc is mounted on the shaft of the hatchet, and a small piece of metal is placed on the disc. When the disc rotates with the hitter axis, the metal block passes over the switch and approaches the switch output + 24V, resulting in a rising edge. When the metal block leaves the proximity switch, the proximity switch outputs 0V, resulting in a falling edge. With the rotation of the driver shaft, the proximity switch outputs a series of pulses. The period from the descending edge of one pulse to the descending edge of another adjacent pulse is the time taken to rotate the beater's axis for a week. By measuring this time, we can get the speed of the shaft.
When the I0.0 is changed from a high level to a low level to produce a rising edge, the T32 of the delay timer is counted from 0. When I0.0 is changed from low level to high level to produce rising edge, the value of T32 is sent to variable memory VW0. At this point, T32 is still counting, that is, the condition of T32>VW0 is established, and the value of T32 is sent to variable memory VW 2. When I0.0 changes from high level to low level, the beater axis rotates for exactly one week. The value in VW2 is the time spent by the beater axis to rotate for one week in MS. At this time, the disconnection delay timer T32 starts counting again from 0. The condition of T32 > VW 0 is not valid. The value of T32 can not be transmitted to VW2, and the VW2 still keeps declining. The value before the arrival is the time that the hatchet shaft rotates for a week.
When choking occurs, in order to reduce the speed of the beater shaft to 15r/s and let the cotton motor stop feeding cotton, a comparison instruction is used in the program to compare the actual speed of the beater shaft VW4 with the set speed of the stop feeding cotton 15 r/s. If VW4 is less than 15r/s, the inequality is not valid. After the delay timer T37 is connected for 2s, the high level relay J of the digital output terminal Q0.0 of the PLC is sucked in, so that the cotton feeding motor stops feeding cotton, thus avoiding the choking death of the cotton opener. When the speed of the beater shaft returns to normal, the inequality is not established. The relay J releases and the cotton motor automatically feeds the cotton. Delay 2s to make relay J suction is to prevent relay J from frequent action when the speed changes near the set value.
The device is not only suitable for opening machine but also for speed control equipment such as carding machine. Moreover, one S7-200 PLC can control multiple equipment, which is low cost, practical and maintenance-free.
