PE DWC pipe production technology and trouble-shooting聚乙烯PE 双壁波纹管生产技术及常见质量问题解决方法

A. Overview of PE double-wall corrugated pipe

1. Definition: The so-called PE double-walled wave tube is a kind of smooth and flat inner wall with trapezoidal or arc-shaped corrugated ribs on the premise of optimizing the cross-section of the tube on the premise of saving raw materials without reducing the ring rigidity of the tube The corrugated wall of the outer wall is hollow, and is made by extrusion molding process. Because its main raw material is polyethylene (PE), it is simply referred to as PE double-wall corrugated pipe.

2. The advantages of PE double-wall corrugated pipe:

① Save raw materials, when using the same raw materials to make pipes with the same outer diameter, bellows can save more than 30% of raw materials by comparison with solid-wall pipes;

② Light weight, the specific gravity is less than 50% of cast iron pipe and cement pipe;

③ Convenient installation and fast construction progress. Compared with traditional cement pipes, the use of PE bellows can increase the installation progress by more than 3 times.

④ PE double-wall corrugated pipe adopts flexible connection with good sealing performance;

⑤Low production cost and superior comprehensive economic performance.

3. Application fields of PE double-wall corrugated pipe

①Municipal engineering, used for underground drainage pipes, sewage pipes, water pipes and ventilation pipes of buildings;

②Electrical and telecommunication engineering, as a protective tube for power cables, optical cables, and communication signal cables;

③In industry, due to the excellent acid, alkali and corrosion resistance of polyethylene materials, structural wall pipes can be used for water supply and drainage pipes in chemical, pharmaceutical, environmental protection and other industries;

④ Agricultural and garden projects, used for irrigation and drainage of farmland, orchards, tea gardens and forest belts, can save 70% of water, save electricity by 13.9%, and can also be used for rural irrigation;

⑤ Road works can be used as infiltration and drainage pipes for railways, highways, golf courses, football fields, etc .;

⑥Mine field, used as mine ventilation, air supply pipe and drainage pipe

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一、PE双壁波纹管概述 

1、定义 ：所谓PE双壁波管是为了在节省原材料而不致使管材的环刚度下降的前提下，对管材截面进行优化设计的一种内壁光滑平整、外壁为梯形或弧形波纹状肋内外壁波纹间为中空、采用挤出成型工艺制成的管材。因为其主要原材料为聚乙烯（PE），故简称为PE双壁波纹管。

2、PE双壁波纹管的优点 ：

① 节约原材料，用同样的原材料做同一外径的管材时，波纹管可经比实壁管节省30%以上的原材料；

② 质量轻，比重小于铸铁管和水泥管的50%；

③ 安装便捷、施工进度快，以传统水泥管相比，采用PE波纹管可以提高3倍以上安装进度。

④ PE双壁波纹管采用柔性连接，密封性能好；

⑤生产成本低，综合经济性能优越。

3、PE双壁波纹管的应用领域 ：

①市政工程，用于建筑物的地下排水管、排污管、输水管、通风管等；

②电器电信工程，作为电力电缆、光缆、通讯信号电缆的保护管；

③工业，由于聚乙烯材料具有优良的耐酸、碱及耐腐蚀能力，结构壁管可用于化工、医药、环保等行业的给水和排水管道；

④农业、园林工程，用于农田、果园、茶园以及林带排灌，可节水70％，节约用电13.9％，也可用于农村灌溉；

⑤道路工程，可用作铁路、高速公路、高尔夫球场、足球场等的渗、排水管；

⑥矿场，用作矿井的通风、送风管、排水管

B. Product performance and national standards

1. Summary and analysis of national standards

National Standard GB / T 19472.1 "Underground Polyethylene (PE) Structural Wall Piping System Part 1 Polyethylene Double-Wall Corrugated Pipe" (Part 2 of this standard is a variety of winding-type structural wall pipes, not related to double-wall corrugated pipes ) This sentence stipulates the use conditions of the bellows. If it exceeds this range, the standard will not necessarily be applicable, and it should be analyzed according to the specific use environment. If there is a project for culverts in Fuzhou this year, the bellows are not buried in the ground, but are placed in the culverts. The culverts will be filled with water during the rainy season. Therefore, the product is used underwater and must be considered in the design buoyancy.

2. Product performance

The three main performance indexes of bellows are ring stiffness, impact resistance and ring flexibility.

l Ring stiffness

The ring stiffness represents the ability of the pipe to resist external pressure, and the unit is kN / m2. The greater the value of the ring stiffness, the stronger the pipe's ability to resist external pressure and the thicker the wall thickness of the corresponding pipe.

l Impact resistance

Using the method of falling-weight impact, the true impact rate (TIR) ≤10% (can be understood as 10 allowed to break 1 but not completely equivalent) under 0 ± 1 ℃ environment. The factors affecting impact resistance are similar to those affecting ring stiffness.

l Ring flexibility

The ring flexibility testing equipment is the same as the ring stiffness, but the compression is greater, and the sample is immediately unloaded when the outer diameter deformation of the sample is 30% of the original outer diameter in the vertical direction. Observe whether the inner wall of the sample remains smooth and there is no reverse bending , Whether it is broken, whether the two walls are detached. Ring flexibility reflects the ability of the pipe to resist deformation.

In addition to ring stiffness, ring flexibility, and impact resistance, the national standard also includes the creep ratio (reflecting the creep of the bellows deformed under external load and affecting the service life of the product) and the oven test (reflecting the combination of the inner and outer walls of the bellows Whether the strength is sufficient and the structural stability) are required.

二、产品性能与国家标准

1、 国家标准摘要及解析

国家标准GB/T 19472.1《埋地用聚乙烯(PE)结构壁管道系统 第1部分聚乙烯双壁波纹管材》（本标准第二部分是各种缠绕类结构壁管，和双壁波纹管无关）这句话规定了波纹管的使用条件，若超出这个使用范围则标准将不一定能够适用，应按照使用环境具体分析。如今年在福州有一个用于涵洞的工程，波纹管并不是埋在地下的，而是置于涵洞中，涵洞中在雨季会充满水，因此产品为水下使用，在设计时就要考虑到浮力。

2、产品性能

波纹管的三大主要性能指标为环刚度、耐冲击性能、环柔性。

l 环刚度

环刚度代表管材抗外压的能力，单位为kN/m2，环刚度的数值越大，则管材抗外压能力越强，相应的管材的壁厚也越厚。

l 耐冲击性能

使用落锤冲击的方法，在0±1℃环境下，真实冲击率（TIR）≤10%（可以理解为10个允许破1个，但是并不完全等同）。影响耐冲击性能的因素与影响环刚度的类似。

l 环柔性

环柔性检测设备与环刚度相同，但是压缩量更大，试样在垂直方向外径变形量为原外径的30%时立即卸荷，观察试样的内壁是否保持圆滑，有无反向弯曲，是否破裂，两壁是否脱开。环柔性反映的是管材耐形变的能力。

除了环刚度、环柔性、耐冲击性能之外，国家标准还对蠕变比率（反映波纹管在外力负载下变形后的蠕变情况，影响产品的使用寿命）和烘箱试验（反映波纹管内外壁结合强度是否足够，结构稳定性如何）有要求。

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C. Raw materials of PE double-wall corrugated pipe

1. Composition of raw materials: The raw materials of PE double-wall corrugated pipes are generally composed of polyethylene, enhanced functional masterbatch and pigments. If the raw materials are wet, in order to improve production efficiency, appropriate defoamers can be added.

2. Requirements for the performance of raw materials: How to produce a low-cost, high-quality corrugated tube depends largely on the choice of raw materials and the combination of formulas.

1) General requirements for the performance of polyethylene (PE) include melt flow rate (MFR), oxidation induction time (OIT) and density. The size of the melt flow rate reflects the size of the molecular weight. Generally speaking, a material with a higher melt flow rate is advantageous for processing and forming, and can improve production efficiency. However, it should not be too large, too large has a greater impact on the ring stiffness, it is appropriate to choose between 0.8-1.5g / 10min (190 ℃, 5kg). Oxidation induction time determines the time of oxidation damage. For bellows requiring 50 years of use, controlling the oxidation induction time of raw materials is the key to ensuring 50 years of service life. GB / T19472.1-2004 clearly stipulates that the oxidation induction time of the raw materials of bellows should be ≥20min (200 ℃). For medium and high density polyethylene, the performance can be adjusted by changing the density. Because we know that polyethylene with relatively low density can prolong its brittle failure time. As shown in Figure 1.

2) The choice of functional masterbatch is also critical. There is no national standard for functional masterbatch for drainage pipes. The performance of products from various manufacturers is not consistent. When selecting functional masterbatch, the dispersibility, coupling and modification degree of polyethylene should be fully considered.

3) Whether the formula is reasonable also determines the quality of the product. In order to reduce costs, some manufacturers add functional masterbatches without restriction. Such products cannot guarantee the quality of the products, but also lose the ability to develop in the long term and compete with the core. The typical reasonable formula is as follows:

三、PE双壁波纹管的原材料  

1、 原料的组成 ：PE双壁波纹管的原材料一般由聚乙烯、增强性功能母料和颜料等组成。如果原材料潮湿，为了提高生产效率，可添加适当的消泡剂。

2、 对原材料性能的要求 ：如何生产出一根低成本，高品质的波纹管，很大程度上取决于对原材料的选择和配方的搭配。

1) 对聚乙烯（PE）性能的一般要求有熔体流动速率（MFR）、氧化诱导时间（OIT）和密度等。熔体流动速率的大小反映了分子量的大小，一般来说，熔体流动速率大一点的材料有利于加工成型，并可提高生产效率。但也不能过大，过大对环刚度的影响较大，选用0.8-1.5g/10min(190℃，5kg）之间为宜。氧化诱导时间决定了氧化破坏的时间，对于要求使用50周年的波纹管来说，控制好原材料的氧化诱导时间是能否保证50年使用寿命的关键。GB/T19472.1-2004中明确规定，波纹管的原材料的氧化诱导时间应≥20min（200℃）。对中、高密度聚乙烯来说，可通过改变密度来调整其性能。因为我们知道密度相对低的聚乙烯可延长其脆性破坏的时间。如图1所示。

2) 功能母料的选择也很关键，目前尚无有关排水管道专用功能母料的国家标准，各厂家的产品的性能不尽一致。选用功能母料时应当充分考虑其分散性、偶联性和对聚乙烯改性的程度。   

3) 配方是否合理也决定着产品的质量。一些厂家为降低成本，无限制的增加功能母料，这样的产品既无法保证产品的质量，也失去了长远的发展和核心竞争的能力。典型的合理配方如下表：

D. the forming principle

1. Forming machine: The bellows forming machine is the key equipment for producing bellows, which is related to the quality and output of the pipe. The forming method of double-wall corrugated pipe is also various and different from other pipe forming equipment.

According to the module assembly method, it can be divided into two types: vertical and horizontal (horizontal). The vertical molding device can open and close the module up and down, and has a small footprint and compact structure, but the module replacement is difficult, especially for large diameter Module replacement; horizontal (also known as horizontal) forming device allows the module to open and close horizontally (usually only large-diameter forming equipment), which occupies a large area, but it is more convenient to replace the module than the vertical type. Moreover, a cooling water circulation channel is designed in the module, and water is used as a cooling medium, which greatly improves the production speed.

According to the setting method, it can be divided into two types: air pressure setting and vacuum setting. At present, some manufacturers use air pressure setting method equipment, which is to pass compressed air through the ribs on the core support of the machine head and the screw plug fixed on the core. Go to the inner cavity of the outer tube blank to make the tube blank tightly adhere to the module to form a wave crest. The products produced by this equipment can be of any cross-section, and can also improve the quality of the bellows, reduce the thickness error on the width of the uneven corrugation, and reduce waste products. It also greatly simplifies the structure of the cooling equipment and the head structure of the product. However, the fluctuation of compressed air makes the peaks of the pipes inconsistent, and the appearance of the product is difficult to control.

2. Forming module: The forming mold of the bellows is mainly a module, which determines the basic structure and size of the pipe. With the different molding methods and the different trajectories of the modules, the structure of the modules is also different. At present, most production lines suck the blank on the inner surface of the mold through the vacuum of the module, and there must be a channel for vacuum on the module. The structure of the forming module directly determines the ring stiffness of the pipe.

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四、成型原理  

1、成型机 ：波纹管成型机是生产波纹管的关键设备，关系到管材的质量和产量。双壁波纹管的成型方式也多种多样，并且不同于其它管材的成型设备。 

按模块装配方式可分为：立式和卧式（水平式）两种 ，立式成型装置可使模块上下开合，并且占地面积小、结构紧凑，但模块更换较困难，特别是大口径模块的更换；水平式（又称为卧式）成型装置可使模块水平开合（通常只有大口径的成型设备），占地面积较大，但更换模块比立式方便。而且模块内设计了冷却水循环通道，以水作为冷却介质，大幅度提高了生产的速度。

按定型方式可分为：气压定型和真空定型两种 ，目前部分厂家采用气压定型法设备，也就是将压缩空气通过机头模芯支座上的筋条和固定在模芯上的螺塞加到外层管坯内腔，使管坯紧贴在模块上，形成波峰。这种设备生产出来的制品可以是任意截面，还可以提高波纹管的质量，减少凹凸波纹宽度上有厚度误差，并且减少废品，还大大简化了制品内冷却设备的结构和机头结构。但是压缩空气的波动使管材的波峰不尽一致，产品的外观较难控制。  

2、成型模块 ：波纹管的成型模具主要就是模块，它决定着管材的基本结构和尺寸。随着成型方式的不同，以及模块运动轨迹的不同，模块的结构也有所不一样。目前大多生产线是通过模块抽真空将料坯吸附在模具内表上，模块上就必须有抽真空用的通道。成型模块的结构直接决定着管材的环刚度。结构如图3所示：

E. Precautions during startup

①Before starting the extruder, you must check whether the temperature of each section is normal. If an abnormality is found, the extruder must be started after the treatment is completed, so as not to damage the screw and other parts or spray the material;

②Start the host after each start condition is met. When starting the host, the melt pressure must be controlled within a certain range to prevent the material temperature from being too high and spraying material to hurt people;

③ Observe the current and pressure of the main machine when extruding. If the current and pressure are too large, you must first check and eliminate the fault before starting up, so as not to damage the equipment;

④Monitor the temperature and sound of the main motor and gearbox at any time, if there is any abnormality, report to the equipment management personnel in time to determine whether to shut down;

⑤ The material of the water jacket is relatively soft, and it cannot collide with metal objects when changing the specifications, and cannot be polished with sandpaper under 800 mesh when dealing with the damaged parts;

⑥ When the molding machine is in normal operation, observe the integrity of all bearings and accessories at any time, and replace and handle it in a timely manner if it is damaged or abnormal;

⑦The lubrication system of the molding machine must be guaranteed to run normally at any time, otherwise the molding machine must be stopped immediately;

⑧ The moving track of the forming machine should be kept clean;

⑨ Must be cleaned every time the module is replaced;

⑩Each time you replace the module, you must check whether all the pins and positioning grooves are intact. If there are abnormal conditions, you must deal with them before installing.

?Transport, installation and disassembly of the module should be extra careful, and any part is strictly prohibited;

?The upper and lower modules (horizontal type are left and right modules) can not be pressed too tight to prevent the module from being deformed or the main motor of the forming machine being overloaded;

?The vacuum pump should regularly clean the scale in the filter and the pump cavity, so as not to affect the vacuum or damage the motor.

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五、开机过程中的注意事项

①挤出机启动之前必须检查各区段温度是否正常，如发现异常，必须待处理完毕后方能启动挤出机，以免损坏螺杆等部件或喷料伤人；

②各开机条件具备后启动主机，刚启动主机时必须将熔体压力控制在一定范围内，以免料温过高而喷料伤人；

③挤出时要观察主机电流和压力，如果电流和压力过大，必须先检查、排除故障后才能开机，以免损坏设备；

④随时监测主电机、减速箱的温度和声音，如有异常，及时报告设备管理人员，确定是否停机；

⑤水套的材质较软，更换规格时不能与金属物相撞，处理损伤处时不能用800目以下的砂纸打磨；

⑥成型机正常运转时要随时观察所有轴承及附件的完好情况，如有损坏或异常要及时更换和处理；

⑦成型机的润滑系统要随时保证运行正常，否则必须立即停止成型机；

⑧成型机的移动轨道要保持清洁；

⑨每次更换模块时必须清理干净；

⑩每次更换模块时必须检查所有的销子和定位槽是否完好，如有异常情况时要处理好后才能安装；

?模块的转运、安装、拆卸要格外小心，严禁损伤任何部位；

?上下模块（卧式为左右模块）不能压得太紧，以防将模块压变形或成型机主电机过载；

?真空泵要定期清理过滤网和泵腔内的水垢，以免影响真空度或损坏电机。

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F. Common problems of PE double-wall corrugated pipe

The use scale of PE double-wall corrugated pipes is getting wider and wider, and the demand for construction is increasing. Many low-quality PE double-wall corrugated pipes on the market are also mixed in there, making huge profits, not being indiscernible by professionals, and forming very serious customers. Big loss. In order to prevent customers from being covered when purchasing, the following editors introduce the common shortcomings of PE double-wall corrugated pipes for us:

1. The inner wall is not flat

The unevenness of the inner wall of the PE double-wall corrugated pipe is usually caused by a low vacuum, a high water jacket temperature, and a thin inner layer. If the vacuum is too low, you should check whether the inner vacuum line is unblocked and whether the vacuum pump is operating normally. Excessively high water jacket temperature is usually caused by too high cooling water temperature or too low cooling water flow rate, which can be dealt with by adjusting these two aspects.

2. Poor flaring. Poor flaring can be divided into the following conditions:

a. The inner layer is blown due to the fact that the inner gas pressure of the inner layer is too large; the raw material resistance is not good; the inner layer is too thin; the flare deflation is started late or the flare deflation pipeline is not clear; there are impurities in the raw materials; Bad chemical and so on.

b. The inner and outer layers of the flaring are not attached properly. If this appearance occurs at the beginning, then the inner layer flushing starts late or the pressure of the corresponding section is too low; if it occurs at the end, the inner layer flushing ends early or expands. The deflation ended prematurely, perhaps because the air pressure in the corresponding section was too low; if it is not attached from beginning to end, it may be the function of the raw material or the temperature.

c. Incomplete flaring The end of the flaring cannot be posted no matter how it is adjusted. The reason is usually that the inner flushing is ended in advance, and the flaring is ended in advance.

d. The inner layer of the front end of the flaring has a concave limit. The reason for this phenomenon is generally that the inner layer flushing starts prematurely; the center line of the water jacket deviates from the current module (the molding machine and the water jacket are not aligned); the inner layer wall thickness Thin; the inner vacuum stops prematurely.

e. The inner layer of material at the end of the flaring, this phenomenon often causes the flaring to be concave inward. The reason is that the inner layer material at the end of the flaring is too thick; the amount of speed reduction of the forming machine in this section is too large; the inner layer of the previous sections is too large; the inner layer material temperature is too high and the billet is too soft; the outer The layer blank is too thick in this section.

f. The inner layer of the end of the flaring has a concave limit. The reason is generally that the air pressure in the first wave and the second wave after the flaring is too small; the first wave after the flaring corresponds to the second wave The inner layer wall thickness is too thick; the inner layer vacuum is low or the inner layer vacuum starts too late; the toughness of the raw materials is poor.

3. There are scratches on the inner layer

Usually, the material temperature is too high, which causes paste to stick to the inner die; impurities in the material; scratches on the water jacket; scratches on the inner die.

4. There are small holes on the outer wall

The reason is that there are impurities in the material; the temperature is out of control in a certain section, causing the material to burn and the material is sometimes taken out; some of the participation in order to improve the function of the pipe, such as the masterbatch and defoamer, are not well dispersed. The compatibility with the base resin is not good.

5. The crest of the pipe is skewed. The speed of the forming machine is too fast and the cooling is not good, and the normal air pressure is too small.

6. The unstable weight of the pipe is generally due to unstable raw material performance or excessive temperature fluctuations in the blanking section.

7. The twists and turns of the pipe are caused by the severe wall of the outer layer or the misalignment between the water jacket and the forming machine.

8. The thickness of the wave crest in the axial direction is inconsistent. It is caused by too large normal air blow and too large gap of the die.

9. The inner wall is uneven. The unevenness of the inner wall is generally caused by low vacuum, excessively high water jacket temperature, and thin inner layer. If the vacuum is too low, check whether the inner vacuum line is unblocked and whether the vacuum pump is working properly. If the temperature of the water jacket is too high, it is generally caused by the high temperature of the cooling water or the flow rate of the cooling water is too small, which can be solved by adjusting these two aspects.

10. The inner layer has scratches

Generally, because the material temperature is too high, paste is stuck on the inner die; there are impurities in the material; scratches on the water jacket; scratches on the inner die.

11. There are small holes on the outer wall

The reason is that there are impurities in the material; the temperature is out of control in a certain section, causing the material to burn and the material is sometimes taken out; the parts such as functional masterbatch and defoamer added to improve the performance of the pipe are not well dispersed, The compatibility of the basic resin (PE) is not good.

12. The brittleness of the pipe after cooling is a relatively common phenomenon, mainly due to the poor performance of the raw materials, such as the proportion of the filler is too large, the quality of the defoamer is poor, and the moisture content in the raw materials exceeds the standard.

13. The ring stiffness is not high. The size of the ring stiffness is related to the performance of the material, the diameter of the pipe, and the design of the wave crest. Generally speaking, it can only be improved by adjusting the performance of raw materials.

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七、PE双壁波纹管常见问题

PE双壁波纹管的使用规模越来越广，施工需求量增大，市场上许多质量低质的PE双壁波纹管也混入其间，牟取暴利，不会专业人员底子无法分辩，对客户形成很大的丢失。为使客户选购时不被遮盖，以下小编为我们具体介绍PE双壁波纹管常见缺点的缘由剖析:

1、内壁不平坦

PE双壁波纹管内壁不平坦通常由真空度偏小、水套温度过高、内层过薄等导致。真空度偏小应当查看内层真空管路是不是疏通，真空泵是不是作业正常等。水套温度过高通常是由于冷却水的水温过高或冷却水的流量过小导致，可通过这两个方面的调整来处理。

2、扩口不良。扩口不良可分为以下几种状况：

a、内层被吹破缘由通常有内层冲气气压过大；原材料耐性欠好；内层过薄；扩口放气发动晚或扩口放气管路不晓畅；原材料内有杂质；物料塑化不良等。

b、扩口内外层未贴好若是这种表象发生在始端，则由于内层冲气发动较晚或相应段的气压过小；若是发生在结尾，则由于内层冲气提前结束或扩口放气提前结束，又或许由于相应段的气压过小；若是从头到尾都没有贴好，则有可能是原材料的功用或温度的缘由。

c、扩口不完整扩口的结尾不管怎样调整都无法贴上，缘由通常是内层冲气提前结束了，扩口放气提前结束了。

d、扩口前端的内层有凹限引起这种现象的原因一般是内层冲气过早启动；水套与在型模块的中线偏离（成型机与水套不对中）；内层壁厚偏薄；内层真空过早停止。

e、扩口末端内层堆料，这种现象往往会导致扩口往里面凹。其原因是扩口末端内层料过厚；成型机在此段的降速的量过大；之前几段的内层冲气过大；内层的料温过高致料坯过软；外层的料坯在此段过厚。

f、扩口末端的内层有凹限其原因一般是扩口后的第一个波和第二个波内的气压过小；扩口后的第一个波和第二个波所对应的内层壁厚过厚；内层真空度较小或内层真空启动过晚；原材料的韧性差等。

3、内层有划痕

通常由于料温过高致使内层口模上粘有糊料；料内有杂质；水套上有划伤；内层口模有划伤等。

4、外壁有小孔

其缘由是物料内有杂质；某区段温度失控致物料烧糊，糊料时而被带出；为了进步管材功用而参加的有些如功用母料、消泡剂等的分散性欠好，或许说与根底树脂的相容性欠好。

5、管材的波峰歪斜 由成型机速度过快冷却欠好、正常冲气气压过小导致。

6、管材的重量不稳定一般是因为原材料的性能不稳定或下料段的温度波动过大。

7、管材曲折 缘由是外层的偏壁严峻或水套与成型机的对中性未调好。

8、轴向上波峰的厚度不一致 正常冲气过大、口模的空隙过大等导致。

9、内壁不平整。内壁不平整一般由真空度偏小、水套温度过高、内层过薄等引起。真空度偏小应当检查内层真空管路是否畅通，真空泵是否工作正常等。水套温度过高一般是因为冷却水的水温过高或冷却水的流量过小引起，可通过这两个方面的调整来解决。

10、内层有划痕

一般因为料温过高致使内层口模上粘有糊料；料内有杂质；水套上有划伤；内层口模有划伤等。

11、外壁有小孔

原因是物料内有杂质；某区段温度失控致物料烧糊，糊料时而被带出；为了提高管材性能而加入的部分如功能母料、消泡剂等的分散性不好，或者说与基础树脂（PE）的相容性不好。

12、管材冷却后脆性大这是一个比较普遍存在的现象，主要是原材料的性能过差所致，比如填充料的比例过大，消泡剂的质量差，原材料内的水分含量超标等。

13、环刚度提不高环刚度的大小和材料的性能、管材的直径、波峰的设计等有关。一般来说只能通过调整原材料的性能来改善。

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