Analysis on the problem of Kaiping line control system
Unwinding, leveling, shearing, stacking production line referred to as Kaiping line. Its task is to roll the steel plate straightening leveling, according to the needs of the product cut into different lengths, yards into the stack after loading shipment.
At present, the Kaiping line mostly adopts automatic control, which is used as the following kinds of controls: Shan Industrial Control machine, it is mostly seen in the large Kaiping line flying shear control. Shan Programmable controller PLC PLC anti-interference ability, stable and reliable work, there are many Kaiping line using PLC control. Shan single-chip Microcomputer, it is particularly suitable for industrial control of the special microcontroller, in the automotive, machine tools, home appliances and many other fields are widely used. It is proved by practice that single chip microcomputer application system has many advantages, such as low cost, flexible output form, and common fault users can deal with the anti-interference problem. Shan counter, the counter in the Kaiping line is usually a simple shearing positioning, it is difficult to achieve some of the special requirements of users. Analysis of Kaiping line production process Control process, ordinary 8-bit microcontroller is fully competent, mainly to solve the anti-interference and positioning accuracy of two major problems.
The composing of Kaiping line numerical control system based on single chip microcomputer, the Kaiping line NC system diagram is shown in Fig. 1, by MCU, keyboard, monitor, 4 times double Frequency double counter frequency circuit, pulse encoder signal conditioning circuit, relay drive circuit and so on several parts. Monolithic computer 89s51 is the control core of the system, its instruction system and so on is identical with 89C51, but its price is cheaper, is 89c51 substitution product. The keyboard is used to set the operating parameters such as length of workpiece, number of continuous machining, advance braking distance, acceleration coefficient and deceleration factor. This system uses the PC machine XT type standard keypad. Each press button, the standard keypad output the key corresponding to the 2-byte scan code, the keypad output 1-byte scan code, through the interface circuit to the Single-chip 1 interrupt requests, MCU in the Interrupt Service Program analysis Scan code and generate the corresponding key values. The standard small keyboard works reliably, eliminates the software to shake, the inquiry key condition and so on operation, causes the monolithic processor to have the more ample time to handle the control operation in the production process.
2 sets of LED seven-segment monitor display system running state, operation parameters, parameter setting value and so on. Only in each digital tube of the COM end of the 1-limit resistor design, simplifying the circuit and wiring, display effect is not reduced. Pulse encoder is a kind of rotary pulse generator, which turns the mechanical turning angle into electric pulse, which can be used as position detection and speed detecting device in NC machine tool and sheet shearing location. Pulse encoder is divided into photoelectric type, contact type and electromagnetic induction type 3 kinds. The photoelectric Pulse encoder is reliable and widely used.
The photoelectric Pulse Encoder produces two sets of current signals, A and B, which are approximate to the sine wave by grating during rotation. Signal A and B phase difference of 90 °, by magnifying plastic into a square wave. There is also a "one-turn pulse" called the Z-phase pulse through the grating. Z-phase pulses are often used to generate the datum points of a machine tool, or as an error correction signal.