This paper briefly introduces the working principle and control system of the hollow forming machine, and introduces in detail the functions of the control system of the hollow forming machine realized by UniMAT PLC, which provides a higher cost performance control system solution for the manufacturers of the hollow forming machine.
1. concept of blow molding machine
Hollow blow moulding machine is mainly used for the production of bottles, pots, cans, barrels and small special-shaped parts and other single-layer, double, (double) visible level line blow moulding hollow products, especially for PVC, PE, PC, PP, PS, PA and other raw materials of hollow blow moulding. The principle of hollow blow molding machine is "extrusion blow molding". Variable frequency motor is used to adjust the speed of extruder, which can not only meet the requirements of different products, but also make the billet stable to ensure the uniformity of product weight. Molten plastic plasticized by extruder is formed by extruder head, and the billet is blown into the mold by compressed air, which completes a cycle. At present, there are large models and small models of hollow blow molding machines on the market. Small models are divided into single station and double station. When working in double stations, the left and right workstations each complete a work process to count a cycle.
Hollow blow molding machine is composed of mechanical, electrical, hydraulic, pneumatic, waterway and servo oil source (selection).
2. system description
Hollow blow molding machine adopts variable frequency motor speed control system; head and extruder heating and temperature control system; action program control system (PLC) and the corresponding safety protection system. The human-machine interface is input by touch screen.
The technological process: the barrel die is heated and kept warm for a certain time - start extrusion - adjust the die to adjust the extrusion forming tube blank - [start - die frame - Clamp - air nozzle - cut tube blank - lift die head - die frame - lower - air nozzle - blow cooling molding - blow pin micro - draw - bottom - open die - die frame] automatic circulation worker Do.
3. control system design
3.1 system principle and configuration
Work process: granular or powdered plastics through the extruder plasticization to melt state, through the collection of electronic ruler data, feedback control of the amount of extrusion melt, so that the melt through a predetermined flow rate into the nose. When the reserve reaches the predetermined value, the die opens, and according to the set blank wall thickness curve, adjust the die core to control the blank wall thickness. Then, the finished product blank is placed in the blow mold cavity, the mold is closed at a set speed, the movement of the mold is stable, left and right balance is required. After the mold is closed, the billet is blown, and the billet is pressed against the inner wall of the mold under the action of gas pressure. After the mold is cooled and finalized by pressure, the mold is opened and the product is removed by the manipulator.
The main configuration of the system electrical control section is as follows:
Single frame machine:
MT4404T 7 inch color screen 1PCS
18DI/30DO 12TC, 2AO depends specifically on the machine.
Double frame machine:
MT4404T 7 inch color screen 1PCS
24DI/32DO 12TC, 2AO depends specifically on the machine.
(1) main UniMAT UN214-1AD23-0XB0 (single rack) and UN216-2AD23-0XB0 (dual rack) control. Structured programming concept, machine manipulator, automatic program, temperature control program, alarm and protection control program, data conversion program and other parts of the program block. Compiled in the revision and testing procedures.
(2) UniMAT module is used in the extended module, and K-type thermocouple is used in the temperature measurement. Temperature control is completed by UN200 series 8-way thermocouple module UN231-7PH22-0XA0 and 4-way thermocouple module UN231-7PD22-0XA0. The module feeds back the collected temperature analog signal to the CPU, automatically adjusts the temperature of each section through the internal program PID of the CPU, accurately controls the temperature of each section, and the precision of static temperature control is at.5. Prove the fluidity of plastic solution.
(3) The clamping pressure is collected by the analog input module UN231-0HF22-0XA0, and the pressure is feedback by the pressure sensor in real time to ensure the clamping pressure is stable; the oil circuit PQ valve is controlled by the UN232-0HB22-0XA0 to control the PQ valve, which is convenient to set the pressure and flow of each oil pressure action.
(4) The control of wall thickness is realized by the input module UN231-0HF22-0XA0, which collects the feedback signals of billet length and die clearance, and then controls the actuator to drive the servo valve by the analog output module UN232-0HB22-0XA0.
(5) The operation panel adopts KINCO high-definition touch screen to complete the blank temperature, action pressure, flow, machine action time parameters, process parameters setting, display, etc. The operation is simple and reliable with menu program control.