At this stage, most of the spraying in my country’s manufacturing industry still relies on traditional manual methods. In order to meet the user’s requirements for paint film thickness and surface quality, additional grinding and re-spraying are often required, resulting in high labor intensity and low operation efficiency for manual spraying, and long-term exposure to paint will cause harm to workers’ bodies. At present, factors such as the difficulty of recruiting workers and the continuous increase in wages have begun to plague the spraying industry. To solve the above problems, it is necessary to consider the automation of the painting line, so as to improve production efficiency and product quality, and reduce operating costs.
Keywords: Haiwell PLC electrostatic spraying automation high-speed pulse output inverter 485 communication
one. Control requirements
Traditional spraying is to spray the paint directly on the glass bottle through a spray gun, then dry it, and then take the excess paint out of the workshop through water, which not only wastes the paint, but also seriously pollutes the environment.
Now it is required to rotate the stainless steel disc moving up and down at high speed, spray the atomized paint 360° to the outer surface of the glass bottle without dead angle, and adjust the forward speed of the glass bottle and the speed of the wine bottle itself through the frequency converter.
Figure 1 Electrostatic spraying
two. The main hardware configuration of the system
PLC selection: T24S0T
The controller selects Haiwell’s T24S0T, the host is powered by 24V DC externally, 16 channels DI, 8 channels DO relay output; it comes with two communication ports (RS232+RS485), which can be extended to 5 communication ports; two channels of 200K high-speed pulse input , 2-way 200K high-speed pulse output; maximum expandable 7 modules. The system needs multiple frequency converters to adjust the speed of the glass bottle, so as to avoid insufficient spraying due to too fast speed, or insufficient spraying due to too slow speed. The T24S0T host has a 485 port, which can be used as a master station or a slave station, supports 1:N networking, supports various man-machine interfaces and configuration software, and can communicate with any third-party equipment with communication functions (such as frequency converters, Meters, barcode readers, etc.) are networked. Therefore, T24S0T can easily communicate with multiple frequency converters.
The rotation of the motor drives the nozzle to move up and down, so that the nozzle can be sprayed on the glass bottle more accurately. T24S0T supports 5 output types: single pulse output, pulse/direction output, forward/reverse rotation output, A-phase/B-phase pulse, and synchronous pulse output. Different output modes can be selected according to the motor output type, and the applicability is wide.
Figure 2 Control cabinet
three. part of the program
Haiwell PLC communication program is simple, no matter what communication protocol you use, you can complete complex communication functions with only one communication command. In this example, the baud rate of the inverter is 9600, and the data format is E, 7, 1. The following is an example program for reading the frequency communication of the inverter.
In this example, the servo adopts the pulse and direction output method, so the PLC hardware configures the pulse output method as pulse/direction output, and realizes the up and down movement of the nozzle through the PLSY high-speed pulse output command. When the number of pulse output is positive, the motor rotates forward, driving the nozzle to move downward; and when the number of pulse output is negative, the motor reverses, driving the nozzle to move upward.
Haiwell PLC has multiple communication ports, each of which can be programmed and networked, and can be used as a master station or a slave station. Support 1:N, N:1, N:N networking. Through Haiwell PLC, it is easy to network with multiple frequency converters, so as to control the movement of glass bottles. Haiwell PLC single machine supports up to 8 channels of 200KHz bi-phase high-speed pulse output, supports acceleration and deceleration pulse output, and multi-segment envelope pulse output functions. The built-in synchronous pulse output function can easily achieve precise synchronous control. The rotation of the motor is controlled by the high-speed pulse output function of Haiwell PLC, thereby driving the movement of the nozzle, which can make electrostatic spraying faster and more efficient.