12.4 夹网成形装置在线视频

同学们好
Hello everyone

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第四节 夹网成形器
Section 4 Twin Wire Former

夹网成形是指
Twin wire forming is a kind of former

在两张成形网间完成
which completes the whole forming process

全部成形过程的成形器
between two forming wires

具有脱水速率快
It has the advantages of fast dewatering rate

封闭成形纸质量好
good quality of closed forming paper

两面差小
small difference between two sides

掉毛掉粉少
less dropping of hair and powder

平滑度好
good smoothness

横幅定量和水分均匀
constant quantity of horizontal scroll and even moisture content

纤维分散好等特点
good fiber dispersion, etc.

如图所示
As shown in the picture

主要分为辊筒成形器
it is mainly divided into roller former

板成形器和刮板-辊筒成形器
plate former and scraper-roller former

夹网成形器的封闭双面
The closed double-sided dehydrating area of the

脱水区如图所示
twin wire former is shown in the picture

纸浆悬浮液从夹网的
The pulp suspension is onto the wire

最大开口端上网
from the maximum opening end of the twin wire

然后进入楔形区
and then enters the wedge-shape zone

悬浮液可以通过两个方向进行脱水
The suspension can be dehydrated in two directions

极大的增加的脱水效率
which greatly increases the dehydrating efficiency

最初的双网成形器
The original double-wire former

是David Webster 于
was invented and published

20世纪50年代发明并公布的
by David Webster in the 1950s

夹网辊筒成形器的机理
The mechanism of the twin wire roller former

是以辊筒进行最初的脱水
is that the roller is used for initial dehydration

在这类夹网成形器上
On this type of twin wire former

浆料是在相对平静
the pulp is dehydrated under relatively

和没有扰动的情况下脱水
calm and undisturbed conditions

纸幅是在浆料和成形网间
The paper web is formed under the condition that there is

基本没有相对运动的条件下成形的
no relative motion between the pulp and the forming wire

纸幅是在胸辊
The paper web is formed and dehydrated

成形辊和真空伏辊
in the section composed of a breast roll

组成的区间上成形和脱水的
a forming roll and a vacuum couch

图为一台夹网辊筒成形器的
The structure of dehydrating distribution picture

结构简图及其脱水分配图
of a twin wire roller former is shown in the picture

其脱水主要通过成形辊的
The dehydration mainly depends on the centrifugal action

离心作用以及真空伏辊的真空作用
of the forming roller and the vacuum action of the vacuum couch

其脱水的工作原理是这样的
The principle of dehydration is as follows

浆自喷浆口喷出后
after the pulp is ejected from the nozzle

在胸辊和成形辊之间的
a pulp wedge is formed on the wire section

两网所夹的网段上形成一个浆液楔子
between the breast roll and the forming roll

浆料与网接触之后
The pulp begins to dehydrate immediately

立即开始脱水
after contact with the wire

并在网面形成纸层
and forms a paper layer on the wire surface

由于两个网在成形辊上
Due to the high-speed circular motion

是作高速的圆弧运动
of the two wires on the forming roller

水分在离心力作用下甩出网外
water is thrown out of the wire under the action of centrifugal force

在成形辊内有约1Kpa的真空度
There is a vacuum degree of about 1Kpa in the forming roller

水分又部分地被吸入到
and the moisture is partly sucked into the

成形辊面的沟槽内
groove of the forming roller surface

纸浆两面快速脱水的结果
As a result of rapid dehydration on both sides of the pulp

在经过成形辊上150°左右的弧长后
the pulp degree increases from 0.7% to 0.8% at the time of feeding

纸浆度从上浆时的0.7～0.8％
to 7% to 8% at the time of leaving the forming roller after

提高到离开成形辊时的7～8％
going through the arc length of about 150° on the forming roller

湿纸幅在两个网夹持下进入伏辊
After entering the couch under clamping of two wires

先经过一段具有
the wet paper web first passes through the positive

7～20kPa压力的正压区
pressure area with a pressure of 7~20 kPa

目的是促进水分在
The purpose is to promote the water discharge from

离心力作用下经上网侧排出
the upper wire under the action of centrifugal force

接着进入一个较窄的无压平衡区
then go into a narrow pressure-free balance zone

进入真空区继续脱水
enter into the vacuum zone for further dehydration

第一真空室较宽
The first vacuum chamber is wider

真空度约3 kPa
the vacuum degree is about 3kPa

第二真空室较窄
the second vacuum chamber is narrower

真空度约5kPa
the vacuum degree is about 5kPa

湿纸幅离开伏辊的干度达20％以上
The degree of dryness of wet paper web leaving the couch is up to 20%

夹网辊筒成形器的优点是
The advantages of twin wire roller former are

传动功率低
low transmission power

网子寿命长
long wire life

可靠性好
good reliability

有提高车速潜力
high potential of increasing speed

纸幅两面差较小
small difference between two sides of paper web

印刷性能好
good printing performance

其缺点是
The disadvantages are as follows

流浆箱浓度较高
the concentration of the flow box is high

纸张针眼较多
the paper needle-eye is more

内结合力较差
the internal binding force is poor

存在粒状匀度问题
and there is a problem of granular homogeneity

现代薄型纸成形器
Modern thin paper former

属于夹网辊筒成形器
belongs to twin wire roller former

其脱水区有“C”或“S”形结构
and its dehydrating area has “C” or “S” shape structure

因此常称之为“C”成形器
Therefore, it is often called “C” former

或“S”成形器
or “S” former

如图为一种新月形成形器
For example, a crescent-shaped former and its

及其脱水分配图
dehydrating distribution picture are as shown in the picture

该成形器是“C”形成形器的发展
The former is the development of the “C” shape former

由于使用特殊设计的流浆箱
The production capacity has been increased

及网和毛毯的应用
by the use of specially designed flow boxes

增加了生产能力
and by the use of wires and blankets

新月形成形器在国内已有应用
Crescent-shaped former has been used in domestic

下面来介绍刮板成形器
The scraper former, which is initially

其是以刮板进行初步脱水的
dehydrated by the scraper, is described below

分为楔形区和压楔形区
It is divided into wedge-shape zone and pressure wedge-shape zone

压力区和真空区
pressure zone and vacuum zone

楔形区和压力区
The wedge-shaped zone and the pressure zone

是主要成形区
are the main forming zones

楔形区是两张成形网
The wedge-shaped zone is the section

逐渐收敛的区段
where two forming wires converge gradually

纸幅最外层的表面
and the outermost surface of the paper web

主要在这一区成形的
is mainly formed in this zone

压力区的脱水是靠刮板
the dehydrating of the pressure zone is achieved

把成形网压弯来实现
by bending the forming wire with a scraper

如图即为一种刮板成形器
A scraper former is as shown in the picture

接下来是夹网“辊筒—刮板”成形器
The following is the twin wire “roller-scraper” former

又称为成形辊脱水板缝隙成形器
also known as the forming roller dehydrating plate gap former

可用于绝大多数纸种的生产
which can be used in the production of most kinds of paper

夹网“辊筒—刮板”成形器的机理
The mechanism of the twin wire “roller-scraper” former

是以刮板和辊筒两者联合进行脱水
is to dehydrate by the combination of the scraper and the roller

这种成形器可明显提高纸张产品质量
This former can obviously improve the quality of paper

对于提高纸张均匀性
They are one of the best forming device at present

两面一致性、改善纤维定向
which facilitate to improve the uniformity of paper

z向结构、表面性能
the consistency of two sides, enhance the fiber orientation

提高细小纤维和填料留着率
z-direction structure, surface performance

提高纸张内结合强度、抗张强度
improve the retention rate of fine fiber and filler

消除各类纸病等方面
improve the paper internal bond strength, tensile strength

都是目前最佳的成形器之一
eliminate all kinds of paper diseases and so on

如图是由Voith公司开发的CFD单元
A CFD unit developed by Voith Company is as shown in the picture

高速运行下的成形器
New requirements have been put forward

特别是当车速超过2000 m／min时
to the former under high-speed operation in the aspects

在工艺技术、机械、自动控制等方面
of technology, machinery and automatic control

都提出了新的要求
especially when the speed exceeds 2000m/min

1、必须合理配置脱水元件
1. Dehydration elements must be rationally configured

2、成形过程中湿纸页在
2. The degree of dryness of wet paper sheet after

各脱水构件后的
each dehydrating member must be

干度必须分配得合理
distributed reasonably during the forming process

成形辊后的湿纸页干度为2%
The degree of dryness of wet paper sheet after forming roller is 2%

多叶饰靴型构件后
the degree of dryness after multi-blade

或D区段后的干度为6%～8%
decorated boot-shape member or D section is 6%~8%

离开成形器送入压榨部
and the degree of dryness of wet paper sheet after leaving

的湿纸页干度应达到17%以上
the former into the press part shall be more than 17%

3、由于车速的提高
3. Due to the increase of speed

必须对带入纸浆中的空气
enough attention must be paid

予以足够的关注
to the air brought into the pulp

其解决方法有
The solutions are as follows

一是对混合稀释纸浆用的
(1) gas-liquid separation of white water

白水进行气液分离
for mixed diluted pulp

二是在成形辊后设置
(2) foam removal or gas-liquid

除泡沫或气液分离装置
separation device after forming roller

三是把成形器设计成直立式
(3) vertical design of the former to

最大限度地减少带入的空气量
minimize the amount of air brought in

4、在真空成形辊成形区段中
4. In the forming section of vacuum forming roller

由于车速的提高
the centrifugal force increases

离心力也随之增大
with the increase of speed

为降低离心力
In order to reduce the influence

对纸页成形的影响
of centrifugal force on paper sheet forming

应采取如下一些措施
the following measures should be taken

一是要适当提高上网纸浆浓度
1) to increase the pulp concentration of onto wire

减小流浆箱唇板开度
reduce the opening of the lip plate of the flow box

降低成形缝隙中的湿纸页厚度
and reduce the thickness of the wet paper sheet in the forming gap

二是要选用具有足够强度的成形网
2) to select the forming wire with sufficient strength

这节就讲到这里
So much for this section

谢谢同学们
Thank you all