12.1 概述在线视频

同学们好
Hello everyone

现在由我向大家讲解
Now let’s learn

“造纸成形装置”
“paper-making forming device”

成形装置又称网部
forming device is also known as wire section

是在流浆箱后的造纸机上
and it is the most important part

最重要的一部分
on the paper machinery after the flow pulp box

纸浆悬浮液在其上面形成纸页
pulp suspension forms the paper sheet on it

其中的纤维交织定形
among which the fibers interweave and form

纸张的基本物理性质
and the basic physical properties of the paper

也随之确定下来
are determined accordingly

随后的压榨、干燥和压光等过程
then the process of pressing, drying and calendaring

只能有限地改善已成形纸幅的性质
can only make a limited improvement of the properties of the formed paper web

因此，最终产品的质量
Therefore, the quality of the final product

和纸机的正常生产
and the normal production of the paper machinery

都与成形装置的操作有密切关系
are closely related to the operation of the forming device

首先学习First let’s learn

第一节 概述
Section 1 Overview

通过概述
Through the overview

我们对成形装置的作用
we have a general understanding of

以及纸幅成形的机理
the function of the forming device

有一个大体的了解
and the mechanism of paper web forming.

成形装置的作用就是
The function of the forming device

将纸浆转化成湿纸幅
is to convert the pulp into a wet paper web

使其达到一定的干度
and make wet paper reach a certain dryness

从而具有一定的物理性能
and thus has a certain physical property

来满足随后压榨过程的要求
to meet the requirements of the subsequent pressing process

在脱水的过程中
The dehydration process is often accompanied

往往伴随着一些细小组分
by the loss of a number of small components

如填料、细小纤维的流失
such as fillers, fine fibers

因此对成形装置提出的要求是
so the requirements for the forming device are

除了需要良好的脱水性能外
in addition to good dehydration performance

还需要保证尽量多的
but also need to ensure that as many

细小组分留着在成形网上
small components as possible remain in the forming wire

并且，纸浆在成形装置上
Moreover, the pulp has undergone the transition

经历了从可流动的悬浮液
from a mobile suspension

到固定的湿纸幅的转变过程
to a fixed wet paper web on the forming device

成形装置必须具有分散纸浆的能力
The forming device must have the ability to disperse the pulp

避免纤维絮聚
avoid the flocculation of the fiber

最终得到均一的纸幅
and finally get the uniform paper web

那么纸幅的成形过程
So what should be the

应该是怎么样的呢
forming process of the paper web

实际上就是纤维悬浮液
In fact, it is the process of dehydrating and deposition

在成形网上脱水和沉积的过程
of fiber suspension in the forming wire

主要是一个流体力学的过程
and is mainly a hydrodynamics process

主要包括三个过程
which consists of three processes

定向剪切、湍动和泄水
directional shear, turbulence and water discharge

从图可以看出
It can be seen from the picture that

定向剪切是尚未泄水的
the directional shear is the shear flow

纤维悬浮体中的剪切流
in the fiber suspension which water is not discharged

有清晰可见的流动方向
which has a clear flow direction

和平均流速的梯度
and a gradient of the average flow velocity

具有分散作用、定向作用和浓集作用
and has the functions of dispersion, orientation and concentration

其中分散作用是指
Wherein the function of dispersion refers to

由于流体流速梯度的存在
that the fiber wire in suspension deforms

悬浮液中纤维网络
under the action of shear force

在剪切力的作用下发生变形
and is eventually dispersed due to the existence

最终被分散
of the gradient of the average flow velocity

定向作用指的是
The function of orientation refers to that

由于定向剪切表现出
most of the fibers deposited in the deposit layer

明显的流动方向性
are arranged along the shear direction

使积层中沉积的纤维多数
due to the obvious

沿着该优势的剪切方向排列
flow directivity of the directional shear

在泄水范围内包含有
When a strong shear flow pattern with non-uniform

非匀布的强剪切流型时
distribution is included in the water discharge range

纤维表现出相应与
the fibers exhibit a concentration trend

剪切场模式的浓集趋势
corresponding to the shear field pattern

这就需要高强度微湍动来抑制它
which requires high-intensity micro-turbulence to suppress it

成形过程中的湍动
The turbulence in the forming process

就是未泄水的自由悬浮体中的
is the non-directional fluctuation of the flow velocity

流速的无定向波动
in the free suspension which water is not discharged

它可以分散纤维网络
it can disperse the fiber wire

在有限的程度上
and make the fiber move easily

使纤维在悬浮体中易动
in the suspension to a limited extent

从而降低其絮聚程度
thus reducing the degree of flocculation

同时也可以作为
and can also be used as a means

定向剪切衰减的手段
of directional shear attenuation

泄水即是水通过成形网的流动
The water discharge is the flow of water through the forming wire

主要按照过滤和浓缩
which is carried out mainly according to the two

两个机理来进行
mechanisms of filtration and concentration

当悬浮体中的纤维是易动的
Filtration occurs when the fibers in the suspension

或可以互相无干涉地自由运动时
are mobile or can move freely without

就发生过滤
interference with each other

当悬浮体中的纤维成为
Concentration occurs when

互相交织的网络状态
the fibers in the suspension

纤维不易动时
become intertwined wire states

就发生浓缩
and the fibers do not move easily

过滤和浓缩两种泄水机理
The two water discharge mechanisms of filtration and concentration

实际上是同时存在的
actually exist at the same time

只是按浓缩机理进行的泄水
but the water discharge according to the concentration mechanism

带有局部性和暂时性
is local and temporary.

下面来介绍一下
Let’s look at the classification

成形器的分类
of the forming device/section

从结构上来说
In terms of structure

可以分为长网、圆网和多网
it can be divided into fourdrinier, cylinder and multi-wire

其中多网成形器
wherein the multi-wire former

又可以分为夹网成形器
can be divided into twin wire forming device

复合型成形器和叠网成形器
compound forming device and overlapped wire forming device

从成形的方式上来区分
it can be divided into single layer and multi-layer

又可以分为单层和多层成形器
forming device according to the forming method

从浓度上来区分
it can be divided into low concentration forming

又可以分为低浓成形和高浓成形
and high concentration forming based on concentration

本节就讲到这里，谢谢同学们
That's all for today, thank you