Analysis of the causes of weight instability in the production of blow molding machines

Analysis of the causes of weight instability in the production of blow molding machines

The blow molding machine is a device for making plastic pellets into hollow containers by a blow molding process. The more common models include a one-shot hollow extrusion blower using PP and PE, which is formed by PET, PC or PP twice. The injection blow molding machine, as well as the newly developed multi-layer hollow extrusion and stretch blow molding.

Most of the blow molding machines are still two-step blow molding machines, that is, the plastic raw materials must first be made into preforms and then blown. Currently commonly used in PET is environmentally friendly plastic. Blow molding machine: After the liquid plastic is sprayed out, the wind is blown out by the machine, and the plastic body is blown to a cavity of a certain shape to make a product. This machine is called a blow molding machine. It is also a type of blow molding machine, namely a hydraulic blow molding machine.

In the production of automatic blow molding machines, the weight of the product is often unstable, and the weight of the product exceeds the specified deviation. The characteristic of unstable weight is that the length of the nozzle at the bottom of the bottle varies. In severe cases, the length of the tube is not enough to make the product not blown. The reasons for the unstable weight are as follows:

1. In the production, the temperature control is inaccurate or the temperature deviation is large. The installation position of the temperature measurement point (thermocouple) is unreasonable, causing the temperature to have a periodic deviation. As the temperature deviation increases, the weight deviation also increases. When the temperature is raised, the extrusion barrel is stretched more, and in the same operation cycle, the nozzle material of the bottom of the bottle is increased, and the weight of the product is reduced. When the temperature is low, the weight of the product is increased. When the thermocouple has poor contact, there is a similar failure. If the thermocouple is broken, the extrusion amount is reduced, and when the temperature is lower than the melting point of the plastic, the motor current increases. Can not be extruded below the melting point of plastic. Whether the installation position of the thermocouple is reasonable and the size of the temperature control of the thermocouple measuring point will directly affect the smoothness of extrusion.

2. The running time of the two mold frames is inconsistent (the difference is too large). If the flow rate of the material pipe is downward, the time difference between the two sides of the left and right mold frames is large, and the weight of the two sides is unstable. The mold frame runs faster and the weight is heavier, and the mold frame runs slower due to the tensile relationship. The solution is to adjust the two side mold bases to make the running time close.

3. The extrusion amount is unstable, and the extrusion amount is unstable due to the unstable rotation speed of the motor and the unsuitability of the belt.

4. The reason for plastic raw materials is different due to the change of the proportion of different plastic raw materials or mixing. How much (percentage) of water-filled material is added often affects the amount of extrusion