Blowing machine debugging skills
Automatic bottle blowing machine temperature adjustment
When the automatic bottle blowing machine is processed, it is necessary to pay attention to some temperature control to ensure that a suitable plastic bottle is manufactured.
1. Melting temperature TM: For crystalline polymers, it refers to the temperature at which the three-dimensional remote ordered state of the macromolecular chain structure changes into disordered viscous flow state, also known as melting point. It is the lower limit of the molding temperature of crystalline polymers.
2. Glass transition temperature TG: refers to the transition temperature of the amorphous polymer (including the non-crystalline part of the crystalline polymer) from the glass state to the highly elastic state or from the latter to the former. It is the lowest temperature for the free movement of the macromolecular segment of the amorphous polymer and the upper limit of the working temperature of the product.
3. No-flow temperature: the highest temperature at which no flow occurs under a certain pressure. The automatic bottle blowing machine is to add a certain amount of plastic to the barrel at the upper end of the capillary rheometer die, and heat it to a certain temperature. After the constant temperature is known to be 10MIN, apply a constant pressure of 50MPA. If the material does not flow out of the die, unload After pressing, the temperature of the material is increased by 10 degrees. After holding for 10 min, the same constant pressure is applied. This continues until the melt flows out of the die. This temperature is reduced by 10 degrees to the non-flow temperature of the material.
4. Flow temperature TF: refers to the temperature at which an amorphous polymer changes from a highly elastic state to a viscous state. It is the lower limit of the processing temperature of amorphous plastics.
5. Decomposition temperature TD: when the temperature of the polymer in the viscous flow state is further increased, the degradation of the molecular chain will increase, and the temperature when the polymer molecular chain is significantly degraded is the decomposition temperature.
The above five points are our summary of how to pay attention to the temperature of the hollow blow molding machine in production, but in general it is not just these five points, which requires us to constantly sum up experience in our daily work to find out that its problems exist .
Production speed adjustment of blow molding machine
By increasing the exhaust time and increasing the saturation time to slow down the speed, and at the same time reduce the overall temperature of the light box, every increase of 0, 1S the overall temperature of the light box needs to be reduced by 1%. Increasing the speed is the opposite of reducing the speed. (The minimum exhaust time is 0, 8S, below 0, 8S, there will be a bottle skipping phenomenon due to the exhaust is not timely.) No matter whether the speed is increased or slowed down, it can not be too fast. Each time, the maximum change is 0, 3S after a period of time. Observe the quality of the bottle and adjust the speed after the bottle quality is stable. Every time you adjust the speed, you must carefully observe the quality of the bottle and adjust the temperature of the light box at any time. Each time the bottle blowing cycle changes by 0, 1S, the bottle output per hour changes by about 50, the bottle blowing machine should adjust the bottle blowing speed reasonably according to the speed of the filling machine.
1. Debugging of plasticizing system
1) The heater of the plasticizing system must be evenly tightened, and the heater and the heated surface should be evenly and tightly attached. For mica heaters, lightly tap with a rubber hammer while tightening to ensure a close fit, which is conducive to uniform heating and prolongs the life of the heater.
2) The thermocouple probe must have sufficient spring preload to ensure accurate temperature measurement.
3) The compression bolts of the die head of the storage cylinder should not be fully tightened. It can be pressed lightly to allow room for the thermal expansion and contraction of the barrel; the axis of the barrel should be kept straight and cannot be bent.
4) Before heating, the cooling water of the barrel and the cooling water of the die head must be turned on to prevent blockage and clogging in the feed section of the barrel, and to prevent the oil seals on the gear box and the die head from aging too quickly.
5) A magnetic rack needs to be placed in the hopper to prevent iron debris from entering the screw, causing damage to the screw and die head parts or clogging of the die head flow channel.
6) When the cold machine is started, it is usually recommended to reduce the extrusion speed. After the tube blank is normally extruded from the die, then gradually increase the speed.
7) Before the tube blank is normally extruded from the die, personnel should not stand directly in front of the die and below the die; when the storage cylinder machine shoots for the first 3 times, personnel should stay away from the die and shoot manually The pressure should not be too large (generally no more than 5MPa).
8) The automatic injection pressure of the storage cylinder machine should not be too large. The actual time of automatic injection is usually greater than 5 seconds. Excessively fast speed may easily lead to inaccurate wall thickness tracking and melt rupture.
9) For machines equipped with a wall thickness control system, the wall thickness controller must be started and run manually once, and then the extrusion can be started to prevent the die from being completely closed and causing damage to the parts.
2. Maintenance of plasticizing system
1) During the operation of the belt transmission pair, the belt may stretch a little, requiring proper tension; the end faces of the two pulleys should be on the same plane; for the coupling drive, the motor shaft and the gear box shaft need to be ensured Concentricity.
2) The gear box needs to be changed regularly. Choose No. 150 (or No. 220) medium extreme pressure industrial gear oil. The new machine uses 500 hours of oil change, and then changes the oil every 3000 hours. When the machine has just stopped working and the gearbox is still at a relatively high temperature, change the oil. After the old oil is drained, flush out the sediment with a small amount of new oil, clean the filter of the lubricating oil pump, and add new oil to 1/2~2/3 of the liquid level window.
3) The temperature of the barrel and the die head is usually above 150 degrees. All fastening screws must be coated with copper disulfide to facilitate disassembly and assembly.
4) The parts of the die head are precisely matched. Disassembly and assembly require special care and skill, not to be exhausted to prevent damage and deformation; the tightening screws need to be tightened diagonally evenly, pay attention to the concentricity and verticality; the multi-die head should pay attention to the center of the die head Distance deviation (<0, 1).
5) The storage piston overflow of the storage cylinder die head needs to be cleaned regularly, generally about 1 week, and the inner mold core overflow usually needs to be cleaned in 3 to 5 years, otherwise the storage stroke and wall thickness control stroke will be affected.
6) Regular inspection: the temperature of the gear box, the temperature of the extrusion motor, the temperature of the root of the barrel and the temperature of the cooling water jacket, and the temperature of the die cooling plate.
7) Safety reminder: the barrel and die head are hot and the heater terminal is live. Pay attention to safety during maintenance and protect it to prevent burns and electric shock.
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Source: Xianji
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