Parison wall thickness control in blow molding is an important step during the production process.
To a certain extent, it affects the quality of blow molded products.
So, how much do you know about parison wall thickness control in blow molding?
This blog will give detailed introduction about this problem.
Why parison wall thickness control in blow molding is important?
For blow molding products:
Blow molding technology is to make the plasticized parison close to the inner wall of mould by air pressure.
Minimum parison wall thickness is specified for the blow molding container products due to its strength requirements.
The parison wall thickness of blow molding products is also a major factor to measure quality.
So, during the production process, to ensure the quality of blow molding products, it requires the parison wall thickness can accurately track the setting value and the responding speed of tracking is fast enough.
The wall thickness of parison is more uniform and stable, the blow molding product is more strong and wearable, the quality is better.
So, parion wall thickness control in blow molding is important.
For plastic blow molding machine manufacturer:
Now, customer’s requirements for blow molding products are becoming more and more diverse.
Such as different capacity, different shape, purpose, layers and so on.
The requirement of layers is related to the parison wall thickness.
If customers want to produce multi-layers blow molding products, it involves the uniformity of every layer wall thickness.
Naturally, the technology of parison wall thickness control in blow molding is needed.
The parison wall thickness control is also helpful to improve the performance of plastic blow moulding machinery.
What is Parison wall thickness control in blow molding? About its principle?
Blow molding process, the material is extruded from the gap of die head after plasticizing, molded by blowing and cooling.
The principle of parison wall thickness is heating the expansion equipment at the lateral mould ring of mould outlet. Adjust expansion equipment temperature by heater.
by the change of expansion volume in different temperature, push forward the radial deformation of mould ring, change the size of mould gap, control the outflow at the mould and change the parison wall thickness.
Generally, there are several thermal expansion equipment installed on the circumference of the mould ring.
Control the interfacial gap of the mould at each point on the circumference to achieve the control effect of parison wall thickness in blow molding.
How to achieve the parison wall thickness control in blow molding?
There are many control methods for blow molding machine, right?
For example, profile mould, axial wall thickness control technology and radial wall thickness control technology and flexible ring technology, edge modification technology, embryo temperature difference method, the combination of vacuum suction and extrusion blow moulding etc.
In addition to these control methods, the corresponding parison wall thickness controller can also be used to cooperate with the blow molding machine.
The method of parison wall thickness control in blow molding machine is
Dividing several points during the molding process of each parison.
Control the parison wall thickness of these points separately.
The fewer the number of control points, the faster the response speed.
But, the control points are too few, it’s hard to achieve the accuracy of parison wall thickness control, and form the weld seam around the parison.
If there are too many control points, it will cause the responding speed too long.
The parison has come out before the servo cylinder can respond to the received signal.
Take MOOG Wall Thickness Controller as an example, many plastic blow molding machine manufacturers adopt MOOG control.
Its independent parison wall thickness control system provides a 30-point and 100-point wall thickness controller (DIGIPACK), which can be used to control the parison wall thickness in blow molding.
Equipped with LCD display can display production status in real time.
In order to achieve better results, you can refer to MOOG Controller: Correct Setting of Core Clearance
The level of plastic blow molding processing machine is depend largely on the level of control.
The blow molding machine with good performance is widely adopt control system with high accuracy.
Fuzzy control, statistical process control (SPC) and network-based remote monitoring and fault diagnosis control systems are used in some high-precision plastic machinery.
In the process of designing and producing of blow molding machine, Yankang Plastic Machinery adopt:
MOOG Control for parison wall thickness control, ensure the stability and uniformity of blow molding products;
Full set of SIEMENS PLC Controller, the operation process is simplified, the production process is more intelligent and accurate, and the operation of blow moulding machine can be monitored in real time by using remote monitoring system.
In a long term, whether it is a plastic machinery manufacturer or a user of plastic machinery, parison wall thickness control in blow molding is a reliable technology to improve the performance of machine or products.