Design of computer monitoring system for the hotte

2022-09-23
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Design of computer monitoring system for magnetron sputtering coating production line

Abstract: This paper introduces the design of a successfully applied computer monitoring system for magnetron sputtering coating production line, and focuses on the hardware configuration, software design, communication protocol, control process implementation and software programming control algorithm of the computer monitoring system

key words: magnetron sputtering coating production line; Computer monitoring system; Easy to control (inspec); Communication protocol; Control algorithm

djw (L) series horizontal (vertical) magnetron sputtering coating production line produced by Zhaoqing Dali Vacuum Equipment Co., Ltd. uses DC power supply or intermediate frequency power supply to control plane target, cylindrical rotating target or intermediate frequency twin target to sputter film on the workpiece. It is widely used in various building glass, ITO transparent conductive glass, household appliance glass, high reflection rearview mirror and acrylic coating industries. While absorbing the advanced technology and coating process of similar European production lines, this series of production lines integrate the unique design concept of humanized operation and simple use, which has been fully affirmed by the user group

in the magnetron sputtering coating production line, a 10.4-inch color touch screen as the main operation interface has become a standard configuration, and the work is relatively stable Because there are many process parameters that need to be controlled in the coating production, in order to greatly improve the work efficiency and the controllability of the coating process, we have designed a set of computer monitoring system to complete the monitoring and parameter optimization of the whole production process, so that the coating production has good technical repeatability and is more suitable for the needs of industrialized mass production

◆ functional design of the monitoring system

according to the working conditions and production requirements of the production line, the computer monitoring system is designed with the following functions

(1) mode selection: in order to meet the working needs of the production line, the computer monitoring system has designed two operation modes - automatic monitoring mode for coating production and manual monitoring mode for commissioning and maintenance. The two operation modes can be switched freely

(2) process scheme selection: in order to realize the coating automation of a variety of workpieces, the monitoring system has designed a variety of process schemes for users to choose. Before the equipment is operated, select the scheme to be used or a new scheme by yourself, and then start the coating production

(3) data detection record: in order to facilitate users to monitor the process, analyze and study the role of process parameters, and adjust process parameters in time to obtain better coating effect, the monitoring system:

1) real time display the power supply voltage, current, vacuum count, gas flow and other parameter values of each magnetic control target

2) regularly record the operation of the equipment, and record the tablet pressing every 30 minutes, or record it at any time as required

3) record important process parameters and form report documents and historical curves

(4) fault alarm record:

1) when the equipment fails, the monitoring system automatically pops up the alarm screen and text prompt, and the alarm light flashes at the same time

2) record all alarm information for query during maintenance; 3) The alarm information can be analyzed according to the fault drawing

(5) automatic diagnosis protection: This is a protective measure to reduce the damage to the equipment caused by faults, mainly manifested in:

1) when the equipment has serious faults, the monitoring system can automatically shut down

2) after the magnetic control power supply is turned on, the voltage and current shall be increased and decreased slowly to protect the power supply

3) it can automatically detect whether the communication between the upper and lower computers is normal

(6) limit of operation authority: this function can limit the authority of general users, prevent misoperation and reduce the probability of error; At the same time, it can also realize the unity of control and monitoring

(7) other functions: the computer monitoring system is also equipped with some practical functions convenient for users to query and use, such as system clock, equipment input and output point monitoring interface, equipment operation instruction interface, etc

◆ composition of monitoring system

this computer monitoring system is composed of three parts: upper computer, lower computer and communication protocol

the hardware structure of the system is shown in the figure

the upper computer is used to monitor the production operation status and production process data, complete all control of the coating production, and take the obtained historical data as a credential for the detection and analysis of the coating effect. Because the environmental interference of the upper computer is small, the ordinary PC is selected, and the operating system adopts Microsoft WindowsXP with good versatility and strong functions. The monitoring and data acquisition software is easy to control developed by Beijing jiusiyi Automation Software Co., Ltd. (why is inspec the dark horse of the material industry favored by the automotive industry?) E20 general configuration monitoring system software is the world's first operating platform based on Microsoft Net has a series of advantages, such as powerful monitoring function, stable performance, exquisite graphics, easy to learn and use, efficient development and easy expansion. It uses high-level language c# as the user program (script) language, which can well meet the requirements of control. The functions of acquisition and data display are also relatively perfect. As long as the device driver is installed, it can communicate with various PLC, intelligent instruments, board cards, frequency converters and other devices, and can also be connected with other computers to form a distributed production management network of an enterprise

the automatic control picture is developed by using the general configuration monitoring system software of easy to control (inspec). Through the upper computer picture, the coating production can be monitored in real time, and the important data can be recorded in the file and saved. When the production is abnormal, the audible alarm and text prompt for out of limit or fault will be given, and the relevant screen will pop up at the same time, so that the operator can quickly analyze and deal with it, so as to resume production in the shortest time. The lower computer is composed of Mitsubishi PLC and various modules, including: a fx2n-128mr host, a fx2n-16eyr output expansion module, four fx2n-4da analog output modules, two fx2n-4ad analog input modules and a fx2n-232-bd communication board

inspec general configuration monitoring system supports OPC server and can be connected to third-party software: since Mitsubishi PLC has a special communication driver, serial port RS-232 shielded cable is used for data exchange between upper computer and lower computer. The data communication between the upper computer and the lower computer is in the form of question and answer. The communication form is that the upper computer sends the communication command (downlink command) to the lower computer, and the upper computer continues to send the downlink command after receiving the corresponding reply command (uplink command) sent back by the lower computer. According to the functional requirements of the monitoring system, the communication protocol adopts periodic command mode to send, and the data transmission adopts event driven communication mode. For the received data communication, the communication protocol is sent to the upper computer after frame length verification, character verification and timeout verification. If an error is found during verification, the retransmission mechanism is applied to retransmit the error frame until it is received correctly

all control work is completed by the lower computer, and the upper computer is only responsible for providing human-computer interaction interface, receiving and sending instructions, automatic process control, data display and storage, parameter setting, report printing, data processing, etc. During the operation of the system, the upper computer always communicates with the lower computer in real time, so as to ensure that the data displayed on the interface is consistent with the actual data; The operation commands issued by the operators on the upper computer and the parameters of the temple can also be sent to the lower computer for execution in real time. Since touch is equipped as a redundant operation equipment, the production line can be switched from the computer monitoring system to the touch screen operation mode at any time without affecting production, which is convenient for equipment maintenance and increases the reliability of the system

◆ control process realization of system process flow design

according to the process requirements of magnetron sputtering coating production line, the coating production control can be designed into four time-sharing action processes

the first process is vacuum acquisition. In order to ensure the quality of coating, the system requires a certain basic vacuum

the second process is ion bombardment. In order to improve the adhesion of the film, high-energy ion bombardment is used to clean the surface of the workpiece to remove the surface and dirt

the third process is magnetron sputtering coating. Electrons from the cathode are affected by Lorentz force in the magnetic field and electric field, and move forward with cycloidal force along the direction of the magnetic field, deposited on the surface of the workpiece and formed a film

the fourth process is the system switching on and off, which is the processing operation of the whole equipment before and after coating

* automatic control design of vacuum acquisition process

the vacuum system of magnetic control coating production line adopts slide valve vacuum pump Roots vacuum pump high vacuum oil diffusion pump unit to obtain low vacuum and high vacuum, and adopts microcomputer digital vacuum meter to detect the vacuum degree. The automatic control of this process includes: ① start and stop control of mechanical pump, diffusion pump, vacuum meter and water pump; ② Output control of high and low vacuum values of each vacuum; ③ Each vacuum valve is used to control the on-off of the vacuum extraction path. The system controls the pneumatic device to open and close the valve

* automatic control design of ion bombardment process

for some models (such as acrylic coating production line), in order to improve the adhesion of the film, the system adopts high-energy ion bombardment as the pretreatment process. In the process of bombardment cleaning, the control indexes are argon mass flow, bombardment voltage, bombardment current, bombardment time and transmission speed; In order to meet the requirements of the coating process, the workpiece can be selected to pass through the bombardment chamber slowly while bombarding; Alternatively, the workpiece can stay in the bombardment chamber and enter the buffer chamber after bombardment for a period of time, which realizes the high-energy ion cleaning of the workpiece

* design of automatic control system for coating process

in order to meet the requirements of coating process, argon mass flow, reaction gas mass flow, sputtering voltage of each target, sputtering current and coating transmission speed need to be controlled in the coating process. When the workpiece moves to the magnetic control target, the target current automatically changes from the maintenance state to the working state, and the workpiece is coated until the workpiece leaves the target and returns to the maintenance state, so as to save the target material to the greatest extent

in order to effectively protect the magnetic control target and the target power supply, the system has designed the water pressure, vacuum degree control and over-current, overheat fault alarm functions, as well as the slow rise and fall function of the target power supply voltage and current

* automatic control design of system switch

automatic startup starts from the preheating of diffusion pump, and the vacuum pumping system automatically works until the vacuum degree of coating chamber reaches, and the magnetic control target automatically starts. All operations in this process are automatically completed by the equipment

automatic shutdown refers to the automatic shutdown of the magnetic control target after the coating work of the production line is completed, and the gradual shutdown of the vacuum pumping system. All operations in this process are automatically completed by the equipment

◆ algorithm control

* feedback algorithm

in the process of system application, there is always a certain error between the set value and display value of the magnetic control power supply. In order to unify the two, our application software has designed a set of feedback algorithm, which is used for the setting and display of power data, and the effect is very ideal

set the current power supply display data (collected data) as x n, after time t, the display data is x n+1, the initial set value of the power supply is S1, and the corrected set value is S2. The specific calculation process is shown in Figure 2

D, K, E in the flow chart are the selected constants X n+1-X n ︳△ =〔S1-(X

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