Application of PLC-controlled pneumatic components in HXFA368 strip-winding machine

1 Introduction

With the rapid development of science and technology, the textile machinery and equipment manufacturing industry has also ushered in a revolutionary development. The current development characteristics of textile machinery and equipment are mainly reflected in: the wide application of touch-type human-machine interface (HMI), programmable logic controller (PLC) and various pneumatic control components; At present, continuously improving the automation of textile machinery and equipment to reduce the labor intensity of operators and improve the production efficiency of textile factories has become an important research and development design purpose of textile machinery manufacturers. The realization of automated actions generally requires the use of PLC to control solenoid valves and cylinders and other actuators. The strip-and-roll combined machine is the most efficient equipment in the combing preparation process in the pre-spinning process. The realization of the automated action of the HXFA368 strip-and-roll combined machine needs to be realized by compressed air driving the cylinder, and the compressed air is controlled by the PLC to control the solenoid valve. The HXFA368 strip-and-roll combined machine uses pneumatic components such as AirTac's solenoid valves and cylinders to realize the execution of automatic actions.

2 Application Design

2.1 Overview of the operation process of HXFA368 strip and roll combined machine

Fig.1 Partial action flow chart of HXFA368 strip and roll combined machine

2.2 Realization of automatic action of HXFA368 strip and roll combined machine

The HXFA368 strip and roll combined machine has the characteristics of a high degree of mechatronics. Its main power is controlled by an 11KW variable frequency motor through frequency conversion to achieve variable frequency speed control. The realization of each step-by-step action is mainly achieved by solenoid valves controlling compressed air to drive cylinders to achieve action control. The actions of emptying pipes up and down, turning cotton rolls, rising and falling of cotton roll holders, pushing cotton rolls, moving the trolley forward, opening and closing of the front protective door, dropping empty pipes from the empty pipe bin, and rising and falling of the empty pipe sending mechanism all correspond to the corresponding solenoid valves and cylinders, and the coordinated operation of the entire action is controlled by a PLC controller. Here is only a brief overview.

2.3 Overview of PLC Programming for Controlling Solenoid Valve

The various automatic actions on the HXFA368 strip and roll combined machine are realized by controlling the solenoid valve with PLC. The following is a step program for controlling some actions.

Figure 2 Step program

PLC coordinates the execution of each cylinder action by detecting the limit points of each automatic action. The cylinder is driven by compressed air controlled by the solenoid valve. Whether the specific action is executed in place is determined by the sensor. The operating speed of the cylinder is adjusted by adjusting the throttle valve.

2.3 Overview of Human-Machine Interface Programming for Controlling Solenoid Valve

In order to facilitate the discrete debugging of various automatic actions on the HXFA368 strip and roll combined machine, Delta DOP-AE10THTD human-machine interface is applied. Through the human-machine interface, the operator can easily realize the real-time control of each solenoid valve, which greatly facilitates the debugging of each automatic action.

2.3.1 The interface design of the human-machine interface control and debugging of the solenoid valve execution action on the HXFA368 strip and roll combined machine.

Figure 3 Interface design

In this interface, the corresponding solenoid valve can be controlled by operating the touch keys such as opening the cotton roll chuck, pushing the cotton roll, and turning the empty tube once. The solenoid valve controls the compressed air to drive the cylinder piston and then realize the corresponding cylinder action. During the debugging of the equipment, the debugging personnel first control the execution of the single-step action through the touch keys in the debugging setting interface, and then adjust the throttle valve according to the actual operation needs to adjust the cylinder running speed.

3 Common faults and solutions in the pneumatic control system of HXFA368 strip and roll combined machine

3.1 Solenoid valve failure

As an actuator, the solenoid valve is controlled by the PLC controller. Since cotton textile equipment is in a 24-hour operation state for a long time, the long-term operation of the solenoid valve is prone to two situations: the solenoid valve fails to close properly or is completely damaged. The solenoid valve fails to close properly on the HXFA368 strip and roll combined machine, which is manifested as an intermittent action failure, which in turn causes the equipment to stop intermittently. In this case, when a single solenoid valve is tested, it is difficult to determine whether the valve body is damaged, and a comprehensive judgment is required based on the specific situation. When the solenoid valve is completely damaged, the fault is that a certain action is not executed. In this case, the corresponding solenoid valve can be replaced according to the actual situation to solve the problem.

3.2 Sensor Failure

During the automatic action execution of the equipment, sensors are needed to detect the limit of the cylinder action so that the PLC can logically coordinate the automatic action of the equipment. The detection sensors are generally of two types: magnetic induction sensors and proximity switches. Once the detection sensor is damaged, the automatic action will stop at a certain action position and will not continue to execute the next action. When encountering such a fault, you should find and replace the corresponding damaged sensor according to the execution of the automatic action.

3.3 Cylinder Failure

As an important actuator, the cylinder will usually leak due to long-term operation. In this case, the cylinder will not move after compressed air is sent into the cylinder, or the movement force and stroke do not meet the corresponding requirements. In this case, the damaged cylinder should be repaired or replaced.