Application of programmable controller in automatic die cutting machine (on)
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Programmable Logic Controller (PLC) is a microprocessor-based dedicated computer for logic control. It takes care of the skills and habits of on-site electrical operation and maintenance personnel. It uses computer software technology to constitute a common relay model. The expression of the computer programming language commonly used in microcomputers is uniquely formed into a set of image programming language based on relay ladder diagram and modular software structure. The user does not necessarily master much computer knowledge. According to the instructions of the PLC manual, It can be programmed directly in accordance with relay ladder diagrams and logic algebra. Therefore, it has the intuitiveness of the relay circuit, is easy to learn, easy to program and debug, and removes the psychological obstacles that people have mystery to the "computer". The PLC technology makes full use of the advantages of the microprocessor to meet various industrial fields. Real-time control requirements, it can freely use the internal functions of the internal relay, timer, counter and other logic functions composed of computer software, the input signal and the internal relay, timer, counter contact can be called multiple times, making programming more flexible, It does not change the hardware and the connection too much due to the program change of the controlled object, and often only needs to modify the user program to meet the new process requirements, which is unmatched by the control device composed of the relay and the sequence controller. In terms of service life, PLC also far exceeds the relay-contactor control system. Therefore, the control system is made safer and more reliable, the downtime caused by the failure is reduced, the maintenance cost is reduced, and the production efficiency is improved. The application of programmable controllers on automatic die-cutting machines now proves that PLC technology is bound to be widely used in various industries.
A leading product automatic die-cutting and creasing machine, the original use of relay-contactor control system, due to the high degree of automation of the machine, a lot of electrical components, making the original system complex, inconvenient wiring, difficult installation, poor maintainability, each The combination of various factors, the original machine control system is not reliable, and debugging is quite difficult. At the same time, due to the backward control technology, the whole machine is low in grade and the competitiveness is not strong. It can only occupy the market by low selling price (relatively speaking). Since August 1989, it has cooperated with Japanese companies to fundamentally control its control system. The transformation, the application of PLC technology, makes the automatic die-cutting and creasing machine look new, greatly improving the reliability and automation degree. After digestion and absorption, it will bloom on the series models (MY680A, MY720, MY920A, MY1020, TYM1020). , bear fruit and fruit. In order to facilitate the introduction of PLC on the automatic die-cutting machine, the requirements of the automatic die-cutting machine for the electrical control system are briefly introduced:
The machine requires automatic paper feeding, automatic die cutting, automatic paper delivery, automatic counting, fault parking alarm, and various security protection functions. The analysis is as follows:
(1) Automatic paper feeding: the operator stacks the cardboard code to be processed on the paper feeding table, and sends the cardboard one by one to the paperboard through the feeder nozzle, and advances one by one with the conveyor belt. . As the paper is continuously sent out, the height of the stack gradually decreases. When the height is lowered to a certain height, a proximity switch is actuated by the automatic paper raising mechanism, so that the motor drives the paper table to rise, and the paper feed continues, and the cycle continues until the All the cardboard is delivered, so that automatic paper feeding is achieved. This section also requires manual lifting and lowering to the paper table.
(2) Automatic die cutting: After the cardboard on the paper conveyor belt reaches the die-cutting section, it must be positioned by the front stop gauge and the side pull gauge, and after the electrical inspection is correct, the cardboard will be fed by the gripper on the gripper. Brought to the die-cutting plate, through the crankshaft four-bar mechanism, the lower platform is pressed and processed, and then the main chain drives the tooth row to bring the processed cardboard to the delivery table.
(3) Automatic delivery: After the processed cardboard arrives, the gripper is opened by the opening mechanism, and the cardboard falls on the delivery table. With the continuous delivery, the height of the stack on the delivery table is continuously increased, making The photoelectric switch is shielded from light, the delivery table is automatically lowered by a distance, the photoelectric switch is reset, and the cycle is continuously performed to realize automatic delivery.
(4) Automatic counting: the cardboard is taken out of the die-cut part by the tooth row and then detected by the reflective photoelectric switch, and then matched with the time-modulated photoelectric switch to realize counting when there is paper, and not counting when there is no paper. In addition, a preset counter can be provided. When the preset number is reached, a signal is sent, and a paper strip is inserted into the stack to later package the semi-finished product according to the preset number.
(5) Fault parking alarm and safety protection setting: The machine is equipped with super high paper, double sheet, paper skew, not in place, paper stack, paper drop, front and rear lock plate, front and rear windows, platform extraction, abnormal paper delivery, left and right Various protection safety switches such as chain and oil pressure abnormality. Any one of these switches requires immediate shutdown. After each switch action, there is a corresponding red diode on the analog panel of the panel to give an alarm indication, which is convenient for the operator to eliminate the fault and shorten the downtime. There are many other functions, limited to the length, not introduced here. Many of the above functions have been realized before the PLC is used, but it is unreliable, faulty, and difficult to maintain.
According to the requirements of the automatic die-cutting machine for the electrical control system, calculate the input points and output points required by the PLC, and select the configuration hardware for the PLC control system accordingly. After calculation, the Fuji NB series host and expansion are selected as the control configuration of the machine, and the active sensing components of the machine are considered. The PLC itself has limited 24V capacity and is equipped with DC regulated power supply (3A, 24V). . After the system configuration is completed, the PLC program is started. Because the program is long, only some of the program segments that highlight the characteristics of the PLC application are listed as follows:
1. Reset control program: The machine uses a large number of transfer switches, that is, the rotary switch that cannot be automatically reset. There is no power failure protection. For example, when the power is off, the switch is in the "ON" position. After the power is turned on, the actuator will act immediately. This kind of non-human control action is extremely It is easy to cause equipment and personal accidents. After carefully reading the PLC manual, it was found that its special relay M8011 has this feature, also known as the "reset flag", so there are the following procedures, the effect is better after application.