罗森太串联挤出机英文资料

CATV

CASCADE Instruction for operating a cascade

List of contents

1) Introduction

preheater

2) Wire

3) Skinextruder

4) Crosshead for skin

system

5) Conveying

station

6) Mixing

extruder

7) Plastifying

8) Cooling

extruder

9) Meltpump

10) Bypass

11) Crosshead for insolation

12) External gas dosing station

13) System of the cascade

14) Gasinjection

15) Gasmeltpressure and gaspressure

16) The foaming process

conditions

17) Starting

18) Relation product parameter – line parameter

the

cascade

19) Operating

20) Stop of the cascade

diagramm

21) Operating

22) Explanations

1 Introduction

The cascade is specially designed for high foamed CATV cable in a high quality. The cable construction without sheat consists of the conductor, the inner skin and the isolation ( see fig. 1).

Fig. 1: cable construction

The inner skin on the conductor is made with the skin – extruder, an vertical extruder. For making the inner skin the group constists of :

a) wire – preheater

b) skinextruder

c) crosshead

The extruder group for isolation consists of following components :

system

a) Conveying

station

b) Mixing

c) Plastifying extruder with gas injection needle and external gas station

extruder

d) Cooling

e) Meltpump

bypass

f) Pneumatic

g) Crosshead

The Cable is made by two extruder groups. For special cables there is an outerskin sometimes. For this production there is an additional extruder for the outer skin

2) Wire preheater

For a good adhaesion between the conductor and the isolation it is in most cases neccessary to preheat the conductor. The wire temperature is depending from the conductor, the wallthickness of the inner skin, the wallthickness of the isolation, the foaming degree and the material mix. Generally the wire temperature is in a range of 20 °C up to 120 °C depending from the wire diameter. For bigger wire diameters the wire temperature is lower than for smaller diameters.

There is a direct influence of the wire temperature, the melt temperature of the skin and the isolation and the forming of bigger bubbles near the conductor. Bigger bubbles near the conductor are formed if the temperatures are too high. If this is happening the wire temperature and the melttemperature of the isolation material should be lower.

3) Skinextruder

The inner skin extruder is a normal vertical extruder. Important is that the extruder is centered very exactly in the production direction.

Usually the skinmaterial is a LDPE and for a better adhaesion it is mixed with some additives. The melttemperature for the skinmaterial is from 140°C - 160°C for bigger cables and 170 °C up to 200 °C for smaller cables. The temperature profil, which is shown in fig. 2, is an example for setting the temperature on RG 11 cable.

° -170°

° -185°

° -200°

° -190°

175° -180° 175° -190°

Fig 2 : Temperatureprofile for skinextruder LDPE ( cable RG 11 )

4) Crosshead

The crosshead is fixed centered crosshead. Usually the wire guide or tip is appr. 0,03 – 0,05 mm bigger than the conductor.The crosshead must be leveled vertical and horizontal to the production direction of the cable. If this is not centered the conductor with the skin is touching the hot tip in the next crosshead and then there are some problems with opening the skin. In that case there are peaks in the capacitance or the material flow of the isolation material is not equal in all directions and the foaming material leaves the die like a snake.

5) Conveying system

For the conveying system there are normal requirements. Specially there is the requirement that the material shouldn′t stand a longer time open in the production hall. Specially in countries with high huminity the material takes water inside and then the foaming process gets very instabil and in most of this cases this material have to be tryed. This fact is important, if the line is stopped over the weekend or over holydays. The conveying system should have short distance to the material, so that no material is standing in the tubes.

6) Mixing station

The mixing station is mixing the material continously. Important is the material mix. The dosing unit is measuring the quantity volumetrical, that means each single chamber, called POCKET, brings a certain quantity of material into the mixing station. For the material mix the number of pockets for one dosing program must be setted. Each of the 3 dosing units have different pocket sizes. Generally there are for dosing unit 3 the size 32, for dosing unit 2 the size 100 and in dosing unit 1 the size 5 or 2 or 1.

For example the materialmix is 75 % HDPE, 24 % LDPE and 1 % Kicker. HDPE 75 % 1000 * 0,75 = 750 necessary volume for HDPE

750 / 100 = 7,5 number of pockets UNIT 2

LDPE 24% 1000 * 0,24 = 240 necessary volume for LDPE

240 / 32 = 7,5 number of pockets UNIT 3

Kicker 1% 1000 * 0,01 = 10 necessary volume for KICKER

10 / 5 = 2 number of pockets UNIT 1 (size 5)

As the setting of the pockets is counting in full chambers it is not possible to set 7,5 pockets. In that fact we multiplicate the number of pockets with 2 to get full number of Pockets.

The setting is then for Unit 2 HDPE 7,5 * 2 = 15

Unit 3 LDPE 7,5 * 2 = 15

Unit 1 Kicker 2 * 2 = 4

The selection what material in what unit is depending from the mix. The highest quantity ( percentage ) is always in the dosing unit with the biggest pocket size and the additive ( the smallest percentage ) is always in the dosing with the smallest pocket size.

7) Plastifying extruder

The plastifying extruder operates as a plasticater and as a mixer. First the granulate must be melted and plastified in the extruder. This is happening in the first four heated extruder zones. In the extruder the gas injection needle is located for the gas injection ( see figure 3 ). There are 2 positions for the gas needle. The position which is used is depending from the screw and the material types, cause some kinds of HDPE need more energy for plastifying and in fact then the needle position 2 is used. Opposite of the gas needle the gasmelt-pressure sensor is located. It gives the information of the actual pressure in the screw at this point.

Position1 add. Position 2 Figure 3 : Plastifying extruder

Temperature Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone6 Flange Head 1 Head2 Position 1 150-170 170-185 185-195190-200175-185170-175165-170 160-165 160-165 Position 2 150-170 165-175 175-190180-195190-200185-195170-180 170-180 165-175

Fig. 4: temperature profiles for needle position 1 and position 2 ( cable RG11)

Before the gas injection the material must be a homogeneous melt. For using needle position 1 or 2 the temperature profiles, as example a RG 11 cable, are a little bit different (see fig.4).The temperature zones 1- 4 for position 1 or zones 1- 5 for position 2 are used to plastify the material. In the following sections the gas ( nitrogen ) is soluted in the melt. In this sections the extruder is working as a mixer.

The high grade of solution and the high grade of mixing is one of the most important requirements for the production.

The connection plastifying extruder and cooling extruder has minimal length and is specially designed for the optimized material flow.

8) Cooling extruder

The cooling extruder is constructed for homogeneization and cooling. Therefor speciall designed screws are used. In this extruder there is a bigger screw, so that the revolutions of the screw are lower. In that fact it is easier to transfer out the energy of the melt.

The temperature profile in this extruder is shown in figure 5. The temperatures are low setted, cause it is necessary to bring out the energy and cool the melt. The melttemperature should not be higher as 150 °C - 170° C at the end of the extruder. In the flange there is the meltpressure sensor located. In the first adapter the melttemperature sensor is placed, which gives the information about the actual melttemperature at the end of extruder 3.

Head 6 Head 5 Head 6

Zone Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Flange Head 1 Head 2 Head 3 Temperature 150-170 150-170 150-170150-170150-170150-170160-175 160-175 155-170 Fig. 5 : Temperatureprofile of Extruder 3 incl. meltpump and Bypass ( RG 11) The setting of all zones is at low level and zone 1 till the flange have almost the same temperature. In head 1 the temperature is higher, cause the next zone is the meltpump.

9) meltpump

For high foamed cables with small tolerances meltpumps are used. The reasons for using a meltpump are as followed:

- reduction of the pressure fluctuations

- constant output of the melt

- linear output at all speeds.

Figure 6 shows the principle of the meltpump.

Figure 6: principle of the meltpump.

The material is under pressure at the inlet of the gear pump. The material is transfered into the chamber of the gears and transfered at the inside of the case and at last the material is displaced.

In a gear pump there are some leakage flows. One of this leakage flows is used for lubricating the wheels. In that fact it is very important that the temperature is high enough for flowing of the material into the small spaces between the bearings and the case. For the setting of the temperature ( see figure 5) it is important that there is increasing of the melttemperature by friction. A minimum increasing of the melttemperature of 10°C – 20 °C is normal in the meltpump. Important is that the meltpump has no influence to the quality of the cable

( attenuation, loss return etc.). Behind the pump the melt must be homogenous.

The meltpump is controlling the output in the whole system over the speed. In that fact the extruder must follow the speed of the meltpump. Therefor it is necessary to have information before the meltpump and behind the meltpump.

In figure 7 there is shown the situation around the meltpump. In the flange of extruder 3 there is the meltpressure sensor placed. The melttemperature sensor is in the adapter. This two sensors are delievering the information before the meltpump. In the adapter between meltpump and bypass there are the pressure

Head 6 Head 5 Head 6

Figure 7: Sensors around the meltpump

Informations about pressure and temperatures are necessary for running the

whole system. The explanation about the relation is in the chapter operating instruction.

10) Bypass

The pneumatic bypass is only for running the extruder without the line. Running

the extruder group without the line is at the start and if the line stops.( tool changing, wire changing etc.). The bypass is generelly switched by the line controller. Only for the start the bypass is opened or closed by the operator.

11) Crosshead

The crosshead is generally a handcentered crosshead. The crosshead consists of

the main case with the distributor inside, the prehead with the leveling screws

and the dieholder with the die. There are 3 separate controlled temperature

zones. The temperature for the mainpart is approximatly 160 ° C. The

temperature setting is increasing till the dieholder. In that way it is possible to to

get a smooth surface. This temperature profile is depending from the material

mix. That means that the temperature at the die is also low or sometimes lower

than the other temperatures on the crosshead.

Zone Head 4 Head 5 Head 6 Temperature 160-170 165-170 160-180 Figure 8: temperatures on the crosshead (cable RG 11)

The centering of the die is placed in the prehead. The centering is made with 4 screws, so that it is possible to move the centerring with the die in all directions. Figure 9 shows an excentric situation.

Figure 9: Excentric conductor in the crosshead

In figure 9 the wire is excentric and it is necessary to make a centering. On the side, where the wallthickness is to small, the screws ( 1 and 2) must be moved out of the head. This movement make the distance between centerring and tip bigger. At the same time the other screws ( 3 and 4) must be moved inside. Before changing the position of a screw it is necessary to mark the top of the cable and the production direction, cause the cable is turning in the cooling trough and the sample is taken in the front of the take-up. In that fact if there is no marking the operator don′t know what is the top of the cable.

Important for the process is the tool design. Specially on the crosshead for the isolation the design of the die is important. There are different ways for designing the die. The best way is a combination of experience and calculation. The diameter of the die is depending from the isolation diameter, the foaming degree, the material mix and the line speed.

Exspecially for bigger cables there is sometime a difference between calculation and experience. Figure 10 shows die design, which are used succesfully.

angle

die

double

angle

Single

die

Figure 10: Die design for CATV-cables

For products with smaller diameters single angle die are used. For high foamed cables and for high dimensions double angle dies are in use.

12) Extrenal gas dosing station

The gas is preapeared for the injection in a external gas dosing station. This can operate manual or automatic by the L2 bus, which is connected with the line controller.

The common way is the automatic operation with the setting from the display of the line controller. There are two possibilities for setting the gaspressure.

a) Gas pressure absolute : The gaspressure is a fixed value. If the extruder is

changing the speed the gaspressure is still the same. That means the

foaming degree is getting lower.

is adding to the gasmeltpressure a

controller

b) Differntialpressure.

The

constant difference pressure and is holding in that way the pressure difference constant. The gaspressure is now following the gasmeltpressure.

13) System of the cascade

The cascade is a multiple extruder system (see figure 11) and consists of a plastifying extruder, a cooling extruder and a meltpump.

Figure 11: Principle of cascade

The extruders and the meltpump are running in a synchron mode, cause one extruder must transfer the melt into the other extruder. So the output of extruder 2 (= plastifying extruder) is the input of extruder 3 (= cooling extruder).The defintion extruder 2, extruder 3 and meltpump or extruder 4 is coming from the whole line design. Extruder 1 is for the inner skin and it is located before the cascade. In this fact the separate skin extruder is extruder 1.

Synchron running means that the extruder speed is in that kind that there is no overfeeding or underfeeding of an extruder. In that fact there are the following requirement:

input extruder 2 = output extruder 2

output extruder 2 = input extruder 3

input extruder 3 = output extruder 3

output extruder 3 = input meltpump

input meltpump = output meltpump ? line speed

For this kind of controlling it is necessary to have a leading parameter. leading parameter.

There is a relation between screw revolution, output and meltpressure. Figure 12 shows this principle relation as an example.

Figure 12 : Output over screw speed

As it is shown in figure 12 the output increase with the increasing screw speed. The meltpressure is getting higher with the screw speed. The meltpressure is depending from the die and from the line speed. In a normal one extruder system a higher revolution of the screw speed means a higher diameter at the same line speed cause it is a open system.

One of the requirements of the cascade system is output meltpump is input meltpump. The input of the meltpump is the output of extruder 3. That means that the speed of the meltpump is limiting the extruder 3.

That means for the required output there is a specific screw speed necessary. As this is now a closed system a higher screw speed is not a higher output it is in that system a higher meltpressure.

In that fact the meltpressure is the leading parameter, which is controlling the screw speed.

The setting of meltpressure 3 is the input pressure of the meltpump. The screw speed is changing to keep the meltpressure constant. The output is at all the time constant, cause it is made by the meltpump.( see figure 13).

Figure 13: Output control on extruder 3

The same principle of controlling the input of the extruder 3 is used. The speed of extruder 3 is now following the meltpump by holding the meltpressure constant. Extruder 3 is running at a certain speed. The input of extruder 3 is made by extruder 2. In that fact extruder 2 must follow extruder 3. At the end of the extruder 2 the meltpressure sensor is placed. By setting this pressure the extruder is changing also the speed to keep the meltpressure constant.

The whole system on the cascade is pressure controlled. The extruders are following automatically to the meltpump and so the line speed in the synchronous mode.

14) Gas injection

The foaming technology knows two kind of foaming:

We don′t see big differences in the way of foaming, if we see the foaming

process itself. The difference is the kind of the additives and the reaction for the following foaming process.

Figure 14 shows the differences between physical and chemical foaming. For high foamed CATV cables we use physical foaming.

For this kind of foaming we need gas. This gas must be soluted in the melt during passing the whole cascade system. The melt must be under pressure in

Chemical foaming Physical foaming

Chemical reaction Physical reaction Foaming additive Azodicarbonamid Foaming add. Nitrogen Foaming degree melttemperature Foaming degree gas quantity

Max. foaming degree ≈ 48 % foaming degree ≈ 48% – 78 % Figure 14: Chemical and physical foaming

As we need gas for the foaming we must bring this gas into the melt. The injection of the gas happens in the plastifying extruder ( = extruder 2). The injection unit is the gas injection needle. Figure 15 shows the diagrammatic view of the gas needle.

Figure 15: overview of the gas injection needle

The gas injection is fixed in extruder barrel. It consists of the housing, the needle, the nitrogen inlet and the needle adjustment. As figure 15 shows the nitrogen is transfered outside of the needle and is injected into the melt at the outlet. The needle is adjustable with the needle adjustment at the end. By moving the needle forward or backward the cross section of the outlet is getting bigger or smaller. Forward moving makes the crossection smaller, moving backward makes the crossection bigger.

The nitrogen is coming from the external gas dosing unit under pressure. At a certain pressure value the crossection is responsible for the quantity of gas. At the same nitrogen pressure a small crossection is reducing the gas quantitv and a

15) Gasmeltpressure and gaspressure

Inside the screw is a pressure. Also at the point of injection the melt is in the extruder under pressure. In that fact the pressure of the gas must be higher than the pressure in the screw. The pressure in the screw is the gasmeltpressure and it is measured by a sensor (see figure 11).

The parameter for the nitrogen pressure is the gaspressure. The requirement is as follows:

gaspressure

? gasmeltpressure

The difference between gaspressure and gasmeltpressure is the differentialpressure and the definition is :

Δgas = p (gas) – p (gasmelt).

The optimized range for the difference between gaspressure and gasmeltpressure is from 60 bar up to 120 bar.

≤Δgas ≤ 120 bar.

bar

60

If the needle has the same crossection then a higher difference brings a higher quantity of gas into the melt. The quantity of gas in the melt gives the foaming degree. That means more gas inside the melt is a higher foaming degree. The foaming degree gives the proportion of gas to solid material. If the quantity of gas is changing then the proportion is changed and the result is another foaming degree. For the specified capacitance there is a specific proportion between gas and solid material ( see figure 16).

Figure 16: Two - component system

For the foaming degree the proportion of gas and solid material is important. The quantity of gas in the melt is made by the differentialpressure, the crossection of the needle outlet and the extruder output. In figure 17 the principle relation between output, gasmeltpressure and gaspressure is shown as an example.

Figure 17 : relation between gasmeltpressure and gaspressure on a single extruder system.

The output of the single extruder is increasing with the extruderspeed. With the higher extruderspeed the meltpressure and the gasmeltpressure is also increasing. For setting the gaspressure there are two possibilities.

One posibility is a constant gaspressure = gaspressure absolute. The gaspressure has a constant value and this means a constant quantity of gas. As figure 16 shows that the difference between gasmeltpressure and gaspressure is changing. So in that fact the foaming degree is changing to. (see figure 19).

The other kind of setting the gaspressure is to set the difference between gasmeltpressure and gaspressure and hold this difference constant. By setting in that way the difference is always constant and also the foaming degree.

The cascade is a meltpressure controlled system and the output is made by the meltpump. The relation between extruderspeed, meltpressure, gasmeltpressure and gaspressure is different from the single extruder system. Figure 18 shows an example for the relations on the cascade.

Figure 18 : relation between gasmeltpressure and gaspressure on a cascade

The gas injection is placed in extruder 2. Extruder 2 is meltpressure controlled, cause the material is transfered in the extruder 3. The controller holds the meltpressure constant and changes the speed. As the meltpressure is constant normally the gasmeltpressure is constant to. The difference between gasmeltpressure and gaspressure is constant in a wide range. With the changing of the screw speed there is no changing of the meltpressure.

If the gaspressure is constant the quantity of gas is constant. The quantity of gas is constant and the output of the extruder is increasing then the proportion of gas and material is changing and the foaming degree is changing to ( see figure 19). Figure 19 shows the changing of the foaming degree by changing the extruder speed with a constant gaspressure.

Figure 19 : Foaming degree over output with a constant gasvolume.

In figure 19 the output of the extruder (solid material) and the gasvolume is in litres per h. With the changing of the extruder output the proportion between gas and material is changing and so the foaming degree is getting lower. In that fact there is no difference between the cascade and the single extruder. The difference to a single extruder is that the meltpressure is constant and there are no fluctuations in the extruder and the running conditions are very constant. During the production the extruders are changing normally not their speeds, cause the conditons are stabil.

With the mode gaspressure absolute it is possible to change the foaming degree with the extruderspeed. A lower speed means less material and in that fact more gas is in the melt and so the foaming degree is getting higher.

16) The foaming process

The foaming of the cable happens behind.As the gas is soluted in the melt and the melt is always under the expansion of the gas is starting after the die under normal atmophere pressure.

The form of the expansion is a cone (see figure 20).

《虚拟仪器设计实验》实验二

实验二、程序结构的使用 一、实验目的 掌握条件结构、循环结构、移位寄存器、顺序结构的使用； 二、实验内容 设计使用循环结构、条件结构、顺序结构控制程序运行的虚拟仪器。具体内容如下：1．求一个数的平方根，当该数大于等于0时，输出开方结果；当该数小于0时，用弹出式对话框报告错误，同时输出错误代码-99999。 2．产生100个随机数并求其最小值和平均值。 3．用随机数（0-1）连续产生0~1的随机数,计算这些随机数平均值达到所用时间。 三、实验步骤 1．求一个数的平方根 启动LabVIEW，打开一个空白的VI。 在前面板窗口适当位置放置一个数值型控制件和一个数值型显示件，并把它们的标签分别修改为“x”和“sqrt(x)”。用编辑文本工具在适当位置，用适当的字体、字号填写实验名称、班级和姓名，图所示前面板供参考。 在框图程序窗口中，从函数模板上找到“大于等于”、“单按钮对话框”，“平方根”和“条件结构”并放置到适当位置，设计框图程序如图所示。 用“姓名实验2-1”为文件名保存你所做工作，如：李红实验。输入x值，运行程序并记录程序运行结果。 图虚拟仪器1的前面板

图虚拟仪器1的框图程序 2．产生100个随机数并求其最小值和平均值 启动LabVIEW，打开一个空白的VI。 在前面板窗口适当位置放置两个数值型显示件，并把它们的标签分别修改为平均值和最小值。用自由“编辑文本”工具在适当位置，用适当的字体、字号填写实验名称、班级和姓名，图所示前面板供参考。 在框图程序窗口中从函数模板上找到“For 循环”并放置到适当位置，为记数端口连接一个32位整型数100；创建两个移位寄存器分别用来从一次循环向下一次循环传递当前最小值和当前随机数累加值；初始化移位寄存器即为移位寄存器左侧端口赋值，设置当前最小值移位寄存器初值为1，当前随机数累加值移位寄存器初值为0，所对应的程序框图如图所示。创建移位寄存器的方法是在循环的左边框或右边框上弹出快捷菜单，然后选择“添加移位寄存器”。 在框图程序窗口中从函数模板上找到“最大值与最小值”、“除”、“加”、“随机数(0~1)函数”，设计框图程序如图所示。

毕业设计外文翻译附原文

外文翻译 专业机械设计制造及其自动化学生姓名刘链柱 班级机制111 学号1110101102 指导教师葛友华

外文资料名称： Design and performance evaluation of vacuum cleaners using cyclone technology 外文资料出处：Korean J. Chem. Eng., 23(6), (用外文写) 925-930 (2006) 附件： 1.外文资料翻译译文 2.外文原文

应用旋风技术真空吸尘器的设计和性能介绍 吉尔泰金，洪城铱昌，宰瑾李， 刘链柱译 摘要：旋风型分离器技术用于真空吸尘器 - 轴向进流旋风和切向进气道流旋风有效地收集粉尘和降低压力降已被实验研究。优化设计等因素作为集尘效率，压降，并切成尺寸被粒度对应于分级收集的50％的效率进行了研究。颗粒切成大小降低入口面积，体直径，减小涡取景器直径的旋风。切向入口的双流量气旋具有良好的性能考虑的350毫米汞柱的低压降和为1.5μm的质量中位直径在1米3的流量的截止尺寸。一使用切向入口的双流量旋风吸尘器示出了势是一种有效的方法，用于收集在家庭中产生的粉尘。 摘要及关键词：吸尘器; 粉尘; 旋风分离器 引言 我们这个时代的很大一部分都花在了房子，工作场所，或其他建筑，因此，室内空间应该是既舒适情绪和卫生。但室内空气中含有超过室外空气因气密性的二次污染物，毒物，食品气味。这是通过使用产生在建筑中的新材料和设备。真空吸尘器为代表的家电去除有害物质从地板到地毯所用的商用真空吸尘器房子由纸过滤，预过滤器和排气过滤器通过洁净的空气排放到大气中。虽然真空吸尘器是方便在使用中，吸入压力下降说唱空转成比例地清洗的时间，以及纸过滤器也应定期更换，由于压力下降，气味和细菌通过纸过滤器内的残留粉尘。 图1示出了大气气溶胶的粒度分布通常是双峰形，在粗颗粒（>2.0微米）模式为主要的外部来源，如风吹尘，海盐喷雾，火山，从工厂直接排放和车辆废气排放，以及那些在细颗粒模式包括燃烧或光化学反应。表1显示模式，典型的大气航空的直径和质量浓度溶胶被许多研究者测量。精细模式在0.18?0.36 在5.7到25微米尺寸范围微米尺寸范围。质量浓度为2?205微克，可直接在大气气溶胶和 3.85至36.3μg/m3柴油气溶胶。

毕业设计方案英文翻译资料中文

故障概率模型的数控车床 摘要：领域的失效分析被计算机数字化控制

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