Development and comparison of electric control sys

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Development and comparison of electrical control system of high-speed tablet press

with the development of the pharmaceutical industry towards large-scale and the improvement of the pharmaceutical industry's requirements for output, control performance and equipment stability and reliability, more and more enterprises have owned or began to consider purchasing high-speed tablet press, as a major manufacturer of high-speed tablet press, This paper attempts to analyze and compare the electrical control systems of high-speed tablet press in the domestic market, so as to help users understand and judge this kind of machine

according to the information we have, the electrical systems of domestic high-speed tablet presses mostly adopt the following three methods: single chip microcomputer, industrial computer and programmable controller (PLC). The following is a comparison of the performance of these three control systems, from which we can also understand the evolution and development of the electrical control system of the high-speed tablet press

1. Single chip microcomputer

but the control accuracy is low

in order to reduce the power noise, the so-called single chip microcomputer system uses the single chip microcomputer CPU and other peripheral chips in the current market, designs the circuit board according to different systems, and finally designs a simple computer system, and designs the program on this basis to achieve the required control function. This form was very popular in China in the 1980s, but due to the limitations of its own reliability and other aspects, it has been gradually replaced by PLC in the industrial field, except that it is still used in the instrument

reliability of single-chip microcomputer: at present, the quality of single-chip microcomputer chips in the domestic market is mixed, and a large part of them are inferior products screened from abroad. In addition, the parameter discreteness of other peripheral components (such as resistance, capacitance, etc.) is also very large. Small batch products cannot be processed by screening and pairing technology, so it is difficult for such products to achieve good consistency and high reliability, Because the parameters of any component deviate from the design requirements, the system will be unstable. In addition, all the devices of the single chip microcomputer are not industrial grade. The anti-interference ability, especially the anti-interference ability of the power supply, is very weak, while the domestic power supply is generally very poor. In addition, the variable frequency speed regulation of the tablet press has a great interference on the power supply. Therefore, it is more likely to cause the instability of the single chip microcomputer system

scalability of single chip microcomputer: since the circuit of single chip microcomputer is specially designed according to certain functional requirements, it is necessary to redesign the circuit and the corresponding programs to add a function. In this way, the development cost and cycle for adding functions will increase

maintainability of single chip microcomputer: once the single chip microcomputer system breaks down, it is difficult to diagnose the faulty components. The simplest way is to replace the whole system, which increases the maintenance cost

operation: at present, the domestic single-chip microcomputer system adopts the self-designed keyboard for operation. The dial switch is used for setting data and the LED is used for display. The whole panel is complicated and locked. Moreover, in order to reduce the number of operation keys, one key is often used for multiple purposes, so it is difficult for the operator to operate without the manual. In particular, the fault display can only display the fault code. Once a fault occurs, the operator must look through the manual to find the fault, and finally eliminate the fault according to the instructions in the manual. In this way, the troubleshooting time is relatively long. In short, such man-machine dialogue is not friendly enough

features: unreliable and cheap. Before 1990, the high-speed tablet press produced by Intertek company used this control mode

2. Industrial control computer

the so-called industrial control computer system is the so-called industrial control computer system in the current market. On this basis, programs are designed to achieve the designed functions. However, the insiders know that there is no essential difference between the industrial computer on the market and the compatible computer assembled by themselves. First of all, the CPU, as the heart of the computer, is as non industrial as the compatible computer, and the other main components such as hard disk, memory, display, etc. are non industrial. The only difference is that the chassis has been reinforced. Due to its own reliability and other limitations, this form is rarely used in industrial sites except for the occasions where the monitor is not directly involved in the control in the factory

reliability of industrial control computer: since the main components of the industrial control computer are not industrial grade, compared with the single-chip microcomputer system, the anti-interference ability, especially the anti-interference ability of the power supply, has been improved to a certain extent, but the domestic power supply is very poor. In addition, the variable-frequency speed regulation of the tablet press has a great interference on the power supply, which may also cause instability of the system

expandability of industrial computer: to add a function, it is necessary to redesign the corresponding program. However, the programming of industrial computer is relatively complex, which will increase the development cycle

maintainability of industrial control computer: once the industrial control computer system has a fault, it is difficult to diagnose the faulty components, which increases the maintenance cycle, and non professionals cannot repair it. If the fault is caused by unreasonable program design and the lack of appropriate debugging tools, it is also difficult to find out the cause of the fault

operation: there is no difference between the operation of industrial computer and general-purpose computer, which has high requirements for the quality of operators. Ordinary workers will be afraid when they see the computer. Although the operation interface is friendly, it is still not simple and easy for people who are not familiar with the computer system

features: the price is in the middle and the reliability is not improved much

3. Programmable controller (PLC):

the so-called PLC system is to use the programmable controller produced by the major industrial control manufacturers in the current market, select the modules with different precision according to the requirements, and design the program on this basis to achieve the designed function. This form is currently the most widely used in industrial field. The gzpk100 series high-speed rotary tablet press produced by our company adopts PLC control mode

plc reliability: the CPU used in imported PLC is a special industrial processor specially designed by the manufacturer, and the other components are also purchased directly from the manufacturer. In addition, its power module is specially designed based on the industrial control experience of major companies, and its anti-interference ability, especially the anti-interference ability of power supply, has been greatly improved, It can work normally even under the interference of poor power supply and variable frequency speed regulation

plc scalability: to add a function, only add the corresponding module and modify the corresponding program, while the PLC programming is relatively simple, which will shorten the development cycle

plc Maintainability: PLC itself has a strong self diagnosis function. Once the system has a fault, it is easy to diagnose the fault components according to the self diagnosis. Even non professionals can repair it. If the fault is caused by unreasonable program design, it is easier to find out the fault because it provides perfect debugging tools

operation: the operation of PLC adopts touch operation terminal, man-machine interface and full screen display, which is designed with a very detailed operation guide. Even if it is used for the first time, it can operate smoothly according to the prompts, which reduces the requirements for operators, and ordinary workers can quickly master it. In addition, once the system fails, the screen will automatically switch to the fault prompt screen to prompt the fault cause and troubleshooting. It can even display the location of the fault on the machine, and the maintenance personnel can quickly eliminate the fault according to the prompts

features: in recent years, the price is slightly higher than that of the first two controllers, with good reliability and simple operation

in addition, the electrical system of gzpk100 high-speed tablet press is designed, manufactured and installed in accordance with IEC standards. The main electrical components are imported from famous foreign manufacturers, thus increasing the reliability of the system. The system adopts the combination of batch chipping and single value chipping, and the single value chipping is one level higher than batch chipping in terms of both effect and technical difficulty

The operation and display of gzpk100a high-speed tablet press are concentrated on the man-machine interface. Except for the start of the main power supply and the emergency stop button, no button operation is required, which greatly reduces the influence of the powder on the electrical components and indirectly improves the reliability of the electrical system. The protection level of human-computer interface is IP67, which can resist various harsh environments. The design idea of centralized operation display is more in line with GMP

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