Various factors affecting PPR pipe quality

发表时间：2020-7-28 9:55:12   浏览：次

1、 Product defect: local discoloration, resulting in uneven and consistent appearance color



① Cause: PP-R pipe is extruded from PP-R resin by extruder. The function of extruder can make PP-R resin plasticize from crystal to high elastic state, and then plasticize to molten viscous flow state. If the heat and pressure of PP-R raw material are improper during extrusion, the molecular configuration will change when the raw material state changes. Too high plasticizing temperature destroys the molecular structure of PP-R and produces decomposition discoloration. At the same time, the extrusion speed is too fast, resulting in high friction heat in the barrel, which increases the material temperature and decomposes and discolors.

② Solution: during the extrusion process of PP-R pipe, it is required to avoid the change of molecular structure of PP-R resin caused by too high plasticizing temperature and too fast extrusion speed



2、 Product defects: surface spots, resulting in uneven appearance and uniform color

① If there is water in PP-R resin raw materials for producing pipes, spots may be formed on the surface of extruded pipes. When the vacuum groove sizing is adopted in the process of extrusion molding and soil adding, if there are bubbles on the pipe in the water tank, spots will also be formed on the surface of the extruded pipe.

② Remove moisture from the raw material or bubbles from the pipe in the sink. In order to ensure that there are no bubbles on the water tank pipe, it is necessary to prevent cavitation of the circulating pump of the water tank, keep the water surface in the water tank above the water inlet, and increase the circulation of water in the water tank.



3、 Product defect: dull surface

① There is moisture in the raw materials for the production of pipes, which may lead to the dull surface of pipes. Improper melt temperature during extrusion, uneven molten materials extruded by extruder, too short sizing sleeve and too short die forming section may lead to dull pipe surface.

② Remove moisture from raw materials or adjust process parameters of pipe processing. Among them, adjusting the technological parameters of the tube processing includes selecting suitable melt temperature, optimizing the uniformity of the extruded extruded melt material, and using the long sizing sleeve to increase the length of the die forming section.



Stabilizer for PRR pipe



4、 Product defect: bright and transparent block

① Excessive head temperature and insufficient cooling.

② Reduce the head temperature and turn up the cooling water.



5、 Product defect: rough and unsmooth surface

① Whether the vacuum degree of vacuum setting is properly controlled or not will directly affect the surface quality of pipes. Too high vacuum degree will make the surface of pipes rough; Too fast cooling speed is easy to produce stress in the pipe, resulting in rough surface of the pipe. In addition, moisture in PP-R resin raw materials will also lead to rough internal and external surfaces of pipes.

② Adjust and control the vacuum degree and cooling speed of the vacuum sizing groove to a good state. Remove moisture from PP-R resin raw materials.



6、 Product defect: bubbles appear on the surface

① When the temperature is too high, the polymer decomposes and bubbles are generated on the surface. The raw material contains water, which may lead to bubbles in the melt and bubbles on the surface of the pipe.

② Control the extrusion temperature of pipe; Remove moisture from PP-R resin raw materials.

7、 Spots and pits on the surface of product defects

① The cooling rate of the extruded tube blank at high temperature has a certain impact on the performance of the product during cooling forming. Too fast cooling is easy to produce stress in the tube and reduce the appearance quality. If the cooling water flow is too large, the pipe surface will be rough and generate spots and pits. The raw material contains water, which may cause pits on the inner wall of the pipe.

② Adjust and control the cooling rate of vacuum sizing groove to a good state. Remove moisture from resin raw materials

8、 Product defect: the hydrostatic test is unqualified

① The raw material of the pipe does not meet the standard requirements, resulting in the mixing of impurities or moisture in the production process, resulting in visible impurities or bubbles on the surface of the pipe, stress concentration will occur at the visible impurities or bubbles, and stress concentration will also occur at the defects such as spots and pits on the surface of the pipe, resulting in the disqualification of the liquid net pressure test of the pipe.

② The use shall comply with GB / t1888742 1 standard PP-R resin, strengthen management and prevent raw materials

Mixed with impurities or moisture. The processing equipment and processing parameters meeting the requirements shall be used to prevent spots, pits and bubbles on the surface of the pipe.