Ningbo Fangli Technology Co., Ltd. is a
mechanical equipment manufacturer with nearly 30 years’ experiences of plastic
pipe extrusion equipment, new environmental protection and new materials
equipment. Since its establishment Fangli has been developed based on user’s
demands. Through continuous improvement, independent R&D on the core
technology and digestion & absorption of advanced technology and other
means, we have developed PVC pipe extrusion line, PP-R pipe extrusion line, PE
water supply / gas pipe extrusion line, which was recommended by the Chinese
Ministry of Construction to replace imported products. We have gained the title
of “First-class Brand in Zhejiang Province”.
In the production process, since PVC is a
kind of heat sensitive material, even if heat stabilizer is added, it can only
increase the decomposition temperature and prolong the stable time without
decomposition, which requires strict control of PVC molding temperature.
Especially for RPVC, since its processing temperature is very close to the
decomposition temperature, often resulting to decomposition due to improper
temperature control. Therefore, the extrusion temperature should be determined
according to the formula, extruder characteristics, die structure, screw speed,
temperature measuring point position, thermometer error, temperature measuring
point depth, etc.
I. Temperature control is an important
factor in extrusion operation. The control factors of extrusion include barrel
temperature, diameter temperature and die temperature. Low temperature, poor
plasticization, dull pipe appearance, poor mechanical properties and product
quality, all these can’t meet the requirements. If the temperature is too high,
the material will decompose and the product will change color.
II. With the increase of screw speed, the
extrusion quantity will increase, so as to increase the output. However, it is
easy to produce poor plasticization, which will lead to rough inner wall and
decrease of strength. For this problem, the head pressure should be adjusted to
achieve the best output and quality. The temperature control of screw affects
the conveying speed, plasticizing and melting quality of materials. The
extrusion pipe needs cooling water, and reducing the screw temperature is
conducive to improving the plasticizing quality. The temperature of the screw
through the cooling water is about 50 ~ 70 ℃.
III. In the re-extrusion operation, it is
very important to adjust the traction speed. After the material is extruded,
melted and plasticized, it is continuously pulled out of the die head and into
the setting device, cooling device and traction device. The traction speed
should match the extrusion speed. Generally, in normal production, the pulling
speed should be 1% ~ 10% faster than the extrusion speed of the pipe.
IV. Compressed air can blow up the pipe to
keep it round. The pressure should be enough. If the pressure is too low, the
pipe is not round, if the pressure is too high, the spindle cools down, the
inner wall of the pipe cracks and is not smooth, and the quality of the pipe
drops. At the same time, the pressure needs to be stable. If the pressure
fluctuates, it is easy to produce crack in the pipe.
V. Different sizing and cooling methods are
used to extrude different plastic products. The cooling medium can be air,
water or other liquid, and the temperature needs to be controlled. The
temperature is mainly related to the production efficiency and the internal
stress of the product.
If you need more information, Ningbo Fangli
Technology Co., Ltd. welcomes you to contact for a detailed inquiry, we will
provide you with professional technical guidance or equipment procurement