UniMAT UN223 module in the control system of the hot-press applications -

introduction

one of our country is lack of material shaolin country in the world, according to experts predict that by 2010 China's timber consumption demand will reach 2. 100 million cubic meters, and the gap of 60 million cubic meters, of which the man-made board industry accounts for a considerable proportion of consumption, thus improving the efficiency of man-made board production is of great significance. Hot press as the key equipment for the production of man-made board, directly determines the production efficiency and product quality, and the stand or fall of hot press performance depends largely on its advantages and disadvantages of the control system. In view of the existing hot-pressing machine adopts relay contact control, make the press control circuit is more complicated, contact too much and the problem of high failure rate, is put forward in the hot-pressing machine control system adopts PLC control, can save part of the relay and atresia contacts, simplify the control circuit, improve equipment reliability. PLC controller CPU224 CN, bring back a UniMAT UN223 module.

a basic working principle,

the hot press is the wood processing industry, scientific research units, institutions of higher learning, such as one of the laboratory equipment, can make fiber board, particle board, plywood, decorative board, plastic board and so on the surface of the compression experiment. In addition to the heating system, its working characteristics and the structure and manufacturing hot press are basically the same. Figure 1 is in this paper, the author studies on hot press the structure diagram. Hot-pressing machine 2 fixed clamp, working through the control located at the base of the press plunger cylinder, makes the plunger 5 driven clamp 4 moving up, the slab compaction; After thermal treatment, plunger 5 driven clamp 4 moves down, after putting in place to prepare for the next work. According to the requirements of man-made board production technology in the process of press work, the key is position control and pressure control system is a speed regulation through proportional flow valve, and then realize the position control.

2, PLC control system, the design idea of

the first thing to satisfy the reliability of equipment in the production. By the size of the original equipment control section components, the control line is complex, the fault is very difficult, therefore, can consider thermal control part adopts the PLC control of the oil cylinder lifting, in meet the requirements of the situation, try to reduce the input and output points, the overall equipment reliability; In addition, considering the equipment repair, maintenance and trial production of the new board, need to add manual and automatic switch control circuit; During maintenance, to prevent the rising pressure plate displacement occurred for wrong operation, equipped with the protection switch, when the switch in the protection state, even if the wrong operation, due to electrical interlock, also not to clamp down. Based on the above design idea, according to the compressor working process, identified the output input of 17 points and 14 points, a total of 31 points, adopting CPU224 products ( The product has 10 input point, 10 dots) Connect UN223 ( The product has 16 input point, 16 output points) 。 Combining with the characteristics of this series of hot press and design the control circuit, and compiled the control program; Addressing input and the output are shown in table 1.

addressing plywood hot press the input and output table 1

three, working principle and control process

to rapidly cover press as an example. This series of hot press is equipped with four cylinder, cylinder overhead, electromagnetic valve control hydraulic circuit need 6, due to the design of hot press different specifications, the oil pump motor power range from 10 to 22 kW, to reduce motor starting current, design for Y/delta starter. Plywood slab used car load, wagon bearing parts can be single direction, the car exits the slab automatic slide on the pressure plate. The car drive motor controlled by frequency converter, which can realize the car fast and slow.

figure 2 for rapid plywood hot press process

control six of the solenoid valve in the cylinder, only one 1 dt for the filling valve; Oil cylinder in two upper and lower oil respectively in parallel, in 2 groups, each group has one upper filling valve 3 dt, 1 only lower suction valve 5 dt and 2, 4, dt, dt and a total oil return valve 6 dt.

lower feed oil cylinder, the column inserting move; The upper feed, the piston moves down. As 1, 2, 4, dt dt dt work, linking piece rise, 1, 3, 5 dt dt dt work, clamp down and pressure; 6 dt work, oil cylinder unloading. Hydraulic oil pump, is driven by three-phase ac asynchronous motor to reduce the starting current need to buck, adopts Y/delta starting, conversion time is 2 ~ 5 s. Oil pump work normal 3 s, linking piece rise in place ( Set a limit switch) After, linking piece stop rising; This fashion plate slab rapidly into the small car, the arrived at the set position, the car unloading slab and began to retreat, retreat after the limit switch to stop.

around the back of the car unloading, at the same time, linking piece begin to decline, when touching the lower limit position switch, stop down, pressure and time, with the increase of oil pressure, moving, or between the clamp pressure, when reach the cap, the limit switch contact monometers, stop the pressure. Required by each solenoid valve automatic control of hot pressing pressure, realize the holding until the end of the hot pressing, start unloading, linking piece rise after 3 s. Completed by artificial plate.

to be on the safe side, add switch in the control circuit, to join in the compressor rise control circuit protection device, when rising pressure plate in place, manually close the switch, maintenance equipment will not make the clamp down by misoperation. At the same time, the compression pressure control circuit, joined the overpressure protection switch, purpose is to prevent oil pressure after reaching maximum pressure continued to pressure. If the overpressure, this switch automatically disconnect, electromagnetic valve closed, losing electricity stop pressure. When the pressure drop to the permission value, the switch is closed again, the system control back to normal.

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