單螺桿擠出機構(gòu)設(shè)計
單螺桿擠出機構(gòu)設(shè)計,螺桿,擠出,機構(gòu),設(shè)計
Extruder
1.General description
By role type extruder can be divided into continuous and non-continuous extrusion extrusion. Plastic extruding machine plastic machine. Plastic extrusion machines in accordance with material flow direction of machine head and screw the angle between the
line from the Center, will head into the bevel head (angle of 120°) and right angle head. On a housing is bolted to the fuselage nose, head of mold core and nuts in the nose into the line port, core with core in front of, core and core the centre hole used by the core wire.
2.machine introduction
Extruder extruder is the host, it consists of extrusion systems, drive systems, and heating and cooling systems.
1. extrusion system for extrusion system consists of screw and barrel, Hopper, die, and die, plastic extrusion system for plasticizing to melt evenly, and, in the process of establishing, under pressure from continuous extrusion screw.
(1) screw: is the main parts of the extruder, it directly concerns the scope of application of extruder and productivity, made from high-strength corrosion-resistant alloy steel.
(2) barrel: is a metal cylinder, generally with higher heat resistance, compressive strength, rugged durability and corrosion resistance of alloy steel or lined steel composite pipe made. Barrel and screw fit, achieve a crushing, softening, melting of the plastic, plastic, exhaust and compacted, and continuous uniform conveying rubber molding system. Barrel length is 15~30 times its diameter, so that the plastic is fully heated and fully plastic into principles.
(3) the hopper: hopper bottom cut off device to adjust and cut the material flow, side of the hopper is equipped with vent and calibration of metering devices.
(4) head and die: die formed by a coat of alloy steel and carbon steel, head mold. Head is the role of the rotary motion of the plastic melt into a parallel linear movement, in a uniform steady import mode, and endows plastics with the necessary pressure. Plastic plastic compaction in the barrel, via porous filter plate along a certain stream of road through the head neck into the head mold, mold mandrel set where appropriate, formation cross sections and constantly reducing the annular space, plastic melt around the wires form a continuous dense coating of tubes. To ensure reasonable channel head plastic, eliminating the accumulation of plastic corners, always placed a shunt socket, for elimination of plastic extrusion pressure fluctuations, there is set of grading rings. Head is also equipped with mould correction and adjustment device, easy to adjust and correct concentricity of the core and die sets.
Plastic extrusion machines in accordance with material flow direction of machine head and screw the angle between the line from the Center, will head into the bevel head (included angle of 120 degrees) and right angle head. Head of shell is with bolt fixed in fuselage Shang, head within of mold has die core sat, and nut fixed in head into line port, die core block of front with die core, die core and the die core block of Center has hole, for through core line; in head Qian Department with are pressure ring, for balanced pressure; squeeze package forming part by die sets block and die sets composed, die sets of location can by bolt through support to regulation, to adjustment die sets on die core of relative location, easy regulation squeeze package layer thickness of uniform sexual. Head external heater and temperature measuring devices.
2. drive screw is the transmission drive system for supply screw Torque required and speed during the extrusion process, usually by the motor, gearbox and bearings and other components.
3. heating and cooling heating and cooling devices are necessary for plastic extrusion process can be carried out.
(1) extrusion presses usually use an electric heating, divided into induction heating and resistive heating, heater installed in each part of the body, neck, and head. Heating device by an external heating cylinder of plastic, making it heated up to processing needed temperature is reached.
(2) the cooling unit is to ensure that the plastic that is set up in the temperature range of technical requirements. Specifically to eliminate rotation of the screw cut the excess heat of friction, in order to avoid high temperature plastic decomposition, scorch or stereotyped difficulties. Machine tube cooling is divided into water-cooled and wind cold two species, General medium squeeze plastic machine used wind cold comparison suitable, large is more used water-cooled or two species Forms combines cooling; screw Rod cooling main used Center water-cooled, purpose is increased material solid conveying rate, stable out rubber volume, while improve products quality; but in hopper Department of cooling, a is to strengthened on solid material of conveying role, prevent due to warming makes plastic grain made stick jam material mouth, II is guarantee drive part normal work.
3.classification
Number usually screw extruder is divided into single-screw extruders, twin screw extruder and multi screw extruders.
Screw-type extruder-plastic systems, heating and cooling systems, transmission systems and electrical control system composed of four parts. Plasticizing screw is the main part of the system, depending on the varieties selection of plastic and its products structure of screw. Extruder screw diameter for 30~250mm at a speed of 30~300R/min. Screw length is usually the diameter of 20~25 times, up to 30 times. Extruding machine cylinder electric heaters heat water or air cooling. Screw conveyor used in extruder machines, commutator motors or DC motors.
4.basic mechanism
Turning in the screw in the cylinder and push the plastic. Screw is actually a ramp or slope, the Twining layer in the Center. Its purpose was to increase the pressure in order to overcome the resistance of larger. An extrusion machine, there are 3 kinds of obstacles need to be overcome: the solid particle (feed) on the screw and cylinder wall friction when turning the first few laps (feed) mutual friction between them; melt adhesion on the wall; the internals of the melt forward logistics and resistance.
5.mechanical principles
In the raw material powder add water or a suitable liquid, stirring constantly. The mixed material using high pressure from the porous head or metal extrusion.
Usually, after the material into a cylindrical container, screw extrusion materials. Using frequency conversion technology, the pressure can be controlled, so that you can select the most appropriate linear speed.
Principles of single-screw extruder
Single screw on the effective length is divided into three sections, deep pitch screw by screw diameter size determine the effective length of the third, usually broken down by each one-third.
Last thread began to call transportation section: material requirements are not plastic, but you want to warm up, squeeze the real, old extrusion theory is that here the items are loosely, and later by showing that the material here is actually solid, which means that after the material is squeezed is a solid plug-like, so as long as the complete conveying tasks is its function.
Compression in the second paragraph, spiral groove volume becomes smaller, and the temperature to achieve the degree of plastic materials, compressed by the conveying section three, here condensed into one, this is called a compression ratio of screw--3:1, some machines also have changed, complete plasticized material will go to the third paragraph.
Paragraph metering section here will keep the plasticization temperature, just accurate, quantitative transmission adopted like metering pumps molten material to supply the head, in which case temperature does not fall below the plasticizing temperature, usually slightly higher.
6.practice
Various types of products in plastic extrusion lines, will have its operating features, a detailed understanding of its operating features before they can fully develop the efficiency of the machine. Is one type of extruder and its a good grasp of extruder operation and correct use of the extruder. Screw extruder including machine installation, adjustment, start-up, operation, maintenance and repair, a series of links, it uses General machines have in common, mainly in terms of drive motor and speed reducer transmission device. Screw extruder system out of the system, but with unique characteristics, use screw extrusion unit should pay special attention to its features.
Machine installation, adjustment and testing of extruder instruction manuals are clear that operation of the extruder, maintenance and service are summarized below:
Operator must be familiar with the structural characteristics of their own of extruder operation, in particular, to correct structural characteristics of screw, heating and cooling the control instrument, die characteristics and Assembly, in order to properly grasp of extrusion conditions, correctly operate the machine
7.control system
Plastic extruder control system including heating systems, cooling systems and process parameter measurement system, primarily by electrical equipment, instrument and executing agencies (namely, operation and control panel). Its main role is to: drag the motor control and the flow adjustment of main engine and auxiliary machine, meet the technological requirements of speed and power output, and enables the coordination of main engine and auxiliary machine; testing and regulation of plastic extrusion machine temperature, pressure, flow, control or automatic control of the whole unit.
Extruder for transmission control and temperature control electric control system is broadly divided into two major parts, the extrusion process, including temperature, pressure, screw speed, screw, barrel cooling, cooling products cooling control of inside and outside diameters, and film speed, straight lines and guarantee take-up from empty to full disk on a disk of constant tension winding control.
1. temperature control of plastic extrusion machine
Wire and cable insulation and sheathing extruder based on deformation properties of thermoplastics, over the edge of the sticky fluid. In addition to requiring external heating screw and barrel, to plastic to make it melt extrusion, also the screw extrusion of plastic itself when heated, therefore requires that the host, the temperature should be considered overall, taking heat heater on and off, but also consider spillover factor screw extrusion heat cooling, there must be effective cooling facilities. And requires proper rational method to determine the location and installation of measuring component thermocouple, temperature control instrument readings accurately reflects the actual temperature of the host segments. Good and requires the precision of temperature control instruments and systems to enable host fluctuations in temperature control system of stability as a whole meets the requirements of all kinds of plastic extrusion temperature.
2. the pressure control of the extruder
In order to reflect the extrusion head, need to detect when the extrusion head pressure, due to the domestic plastic extrusion machine without pressure sensor head, generally for thrust measurement as an alternative after the screw head pressure measurement, load table screw (ammeter or voltmeter) accurately reflects the size of extrusion pressure. Extrusion pressure fluctuations, causing extrusion quality is one of the important factors of instability, extrusion pressure fluctuation and the extrusion temperature, cooling, closely related to factors such as length of continuous operation. When an exception happens when would preclude removing them immediately, must reorganize production should be decisively shut down, can prevent the increase in waste, can prevent the occurrence of accidents. By detecting the pressure gauge reading, you can know the stress of plastic extrusion, generally takes thrust after the limit value alarm control.
3. screw speed control
Screw speed regulation and stability are important technological requirements of the host drive. Screw RPM directly determine the amount of glue and extrusion speed, normal production wants to achieve the highest possible speed and achieve high yield, requirements for extruder screw speed from start to the desired speed, speed range available for use. Stability of rotating speed and high speed fluctuations will result in output volatility, affecting the quality of extrusion, so the traction line under speed does not change, it will cause the cable outer diameter changes. Same as traction device for wire-speed movement also results in changing the cable diameter, screw speed and traction line may be reflected by sitting the appropriate instrument, squeeze should closely observe to ensure high quality and high yield.
4. the outer diameter of the cable outer diameter size of control as described above in order to ensure that products, in addition to control core (core) outside the tolerance, in the extrusion temperature, screw speed, line speed should be controlled to ensure traction device, measurement of outer diameter control are integrated reflecting the above level of precision and control. Plastic extrusion units, particularly on high-speed extrusion production line should be equipped with on-line diameter measuring instrument, test the cable outer diameter at any time, and the variance signal feedback to adjust the speed of traction or screw, correct outside diameter variances.
5. the winding requirements of tension control
In order to ensure different speed of take-up, from empty to full tension requirement hope line take-up device have the tank thread tension adjustment, or consider constant linear velocity in electrical systems and constant tension control system of rewinding, and so on.
6. complete machine of electric automatic control
This is high speed extrusion lines for the process control requirements of, inter alia: power on temperature interlock working pressure protection and interlock material synchronous control, towing two large transmission ratios; take-up and traction control; od-line detection and feedback control; according to different needs of single components and machine track control
擠出機
1.概述
擠出機按作用類型可分為連續(xù)擠出和非連續(xù)擠出。塑料擠出機也是塑料機械的一種。擠塑機按照機頭料流方向和螺桿中心線的夾角，將機頭分成斜角機頭（夾角120°）和直角機頭。機頭的外殼是用螺栓固定在機身上，機頭內(nèi)的模具有模芯坐，并用螺帽固定在機頭進線端口，模芯座的前面裝有模芯，模芯及模芯座的中心有孔，用于通過芯線。
2.機器介紹
塑料擠出機的主機是擠塑機，它由擠壓系統(tǒng)、傳動系統(tǒng)和加熱冷卻系統(tǒng)組成。
1.擠壓系統(tǒng)擠壓系統(tǒng)包括螺桿、機筒、料斗、機頭、和模具，塑料通過擠壓系統(tǒng)而塑化成均勻的熔體，并在這一過程中所建立壓力下，被螺桿連續(xù)的擠出機頭。
（1）?螺桿：是擠塑機的最主要部件，它直接關(guān)系到擠塑機的應(yīng)用范圍和生產(chǎn)率，由高強度耐腐蝕的合金鋼制成。
?。?） 機筒：是一金屬圓筒，一般用耐熱、耐壓強度較高、堅固耐磨、耐腐蝕的合金鋼或內(nèi)襯合金鋼的復(fù)合鋼管制成。機筒與螺桿配合，實現(xiàn)對塑料的粉碎、軟化、熔融、塑化、排氣和壓實，并向成型系統(tǒng)連續(xù)均勻輸送膠料。一般機筒的長度為其直徑的15～30倍，以使塑料得到充分加熱和充分塑化為原則。
（3） 料斗：料斗底部裝有截斷裝置，以便調(diào)整和切斷料流，料斗的側(cè)面裝有視孔和標定計量裝置。
?。?） 機頭和模具：機頭由合金鋼內(nèi)套和碳素鋼外套構(gòu)成，機頭內(nèi)裝有成型模具。機頭的作用是將旋轉(zhuǎn)運動的塑料熔體轉(zhuǎn)變?yōu)槠叫兄本€運動，均勻平穩(wěn)的導(dǎo)入模套中，并賦予塑料以必要的成型壓力。塑料在機筒內(nèi)塑化壓實，經(jīng)多孔濾板沿一定的流道通過機頭脖頸流入機頭成型模具，模芯模套適當配合，形成截面不斷減小的環(huán)形空隙，使塑料熔體在芯線的周圍形成連續(xù)密實的管狀包覆層。為保證機頭內(nèi)塑料流道合理，消除積存塑料的死角，往往安置有分流套筒，為消除塑料擠出時壓力波動，也有設(shè)置均壓環(huán)的。機頭上還裝有模具校正和調(diào)整的裝置，便于調(diào)整和校正模芯和模套的同心度。
擠塑機按照機頭料流方向和螺桿中心線的夾角，將機頭分成斜角機頭（夾角120度）和直角機頭。機頭的外殼是用螺栓固定在機身上，機頭內(nèi)的模具有模芯坐，并用螺帽固定在機頭進線端口，模芯座的前面裝有模芯，模芯及模芯座的中心有孔，用于通過芯線；在機頭前部裝有均壓環(huán)，用于均衡壓力；擠包成型部分由模套座和模套組成，模套的位置可由螺栓通過支撐來調(diào)節(jié)，以調(diào)整模套對模芯的相對位置，便于調(diào)節(jié)擠包層厚度的均勻性。機頭外部裝有加熱裝置和測溫裝置。
2.傳動系統(tǒng) 傳動系統(tǒng)的作用是驅(qū)動螺桿，供給螺桿在擠出過程中所需要的力矩和轉(zhuǎn)速，通常由電動機、減速器和軸承等組成。
3.加熱冷卻裝置 加熱與冷卻是塑料擠出過程能夠進行的必要條件。
（1） 現(xiàn)在擠塑機通常用的是電加熱，分為電阻加熱和感應(yīng)加熱，加熱片裝于機身、機脖、機頭各部分。加熱裝置由外部加熱筒內(nèi)的塑料，使之升溫，以達到工藝操作所需要的溫度。
（2） 冷卻裝置是為了保證塑料處于工藝要求的溫度范圍而設(shè)置的。具體說是為了排除螺桿旋轉(zhuǎn)的剪切摩擦產(chǎn)生的多余熱量，以避免溫度過高使塑料分解、焦燒或定型困難。機筒冷卻分為水冷與風(fēng)冷兩種，一般中小型擠塑機采用 風(fēng)冷比較合適，大型則多采用水冷或兩種形式結(jié)合冷卻；螺桿冷卻主要采用中心水冷，目的是增加物料固體輸送率，穩(wěn)定出膠量，同時提高產(chǎn)品質(zhì)量；但在料斗處的冷卻，一是為了加強對固體物料的輸送作用，防止因升溫使塑料粒發(fā)粘堵塞料口，二是保證傳動部分正常工作。
3.分類
擠出機通常按螺桿數(shù)目分為單螺桿式擠出機、雙螺桿式擠出機和多螺桿式擠出機。
螺桿式擠出機由塑化系統(tǒng)、加熱與冷卻系統(tǒng)、傳動系統(tǒng)和電氣控制系統(tǒng)四部分組成。塑化系統(tǒng)的主要部件是螺桿，根據(jù)塑料及其制品的品種選擇不同結(jié)構(gòu)的螺桿。常用擠出機的螺桿直徑為30～250mm，轉(zhuǎn)速為30～300r/min。螺桿長度通常為直徑的20～25倍，最大為30倍。擠出機機筒多用電加熱器加熱而用水或空氣冷卻。螺桿式擠出機擠出機所用的傳動機多為整流子電動機或直流電動機。
4.基本機理
一個螺桿在筒體中轉(zhuǎn)動并把塑料向前推動。螺桿實際上是一個斜面或者斜坡，纏繞在中心層上。其目的是增加壓力以便克服較大的阻力。就一臺擠出機而言，有3種阻力需要克服：固體顆粒（進料）對筒壁的摩擦力和螺桿轉(zhuǎn)動前幾圈時（進料區(qū)）它們之間的相互摩擦力；熔體在筒壁上的附著力；熔體被向前推動時其內(nèi)部的物流阻力。
5.機械原理
在原料粉末里添加水或適當?shù)囊后w，并進行不斷的攪拌。將攪拌好的材料，用高擠出壓力從多孔機頭或金屬網(wǎng)擠出。
通常是把材料放入圓筒形容器以后，用螺桿擠出材料。在使用變頻技術(shù)以后，可對壓力進行控制，從而可以選擇最合適的線性速度。
單螺桿擠出機原理
單螺桿一般在有效長度上分為三段，按螺桿直徑大小螺距螺深確定三段有效長度，一般按各占三分之一劃分。
料口最后一道螺紋開始叫輸送段：物料在此處要求不能塑化，但要預(yù)熱、受壓擠實，過去老擠出理論認為此處物料是松散體，后來通過證明此處物料實際是固體塞，就是說這里物料受擠壓后是一固體象塞子一樣，因此只要完成輸送任務(wù)就是它的功能了。
第二段叫壓縮段，此時螺槽體積由大逐漸變小，并且溫度要達到物料塑化程度，此處產(chǎn)生壓縮由輸送段三，在這里壓縮到一，這叫螺桿的壓縮比－－3：1，有的機器也有變化，完成塑化的物料進入到第三段。
第三段是計量段，此處物料保持塑化溫度，只是象計量泵那樣準確、定量輸送熔體物料，以供給機頭，此時溫度不能低于塑化溫度，一般略高點。
6.操作規(guī)程
塑料擠出生產(chǎn)線中各個類型產(chǎn)品，都有其操作特點，對其操作特點有個詳細的了解，才可以充分發(fā)揮機器的效能。擠出機是其中一種類型及其，把握好擠出機的操作要點，正確合理地使用擠出機。螺桿擠出機的使用包括機器的安裝、調(diào)整、試車、操作、維護和修理等一系列環(huán)節(jié)，它的使用具有一般機器的共性，主要表現(xiàn)在驅(qū)動電機和減速變速裝置方面。但螺桿擠出機的工作系統(tǒng)即擠出系統(tǒng)，卻又獨具特點，在使用螺桿擠出機時應(yīng)特別注意其特點。
機器的安裝、調(diào)整、試車一般在擠出機的使用說明書中均有明確規(guī)定，這里對擠出機的操作要點，維護與保養(yǎng)簡述如下：
操作人員必須熟悉自己所操作的擠出機的結(jié)構(gòu)特點，尤其要正確掌握螺桿的結(jié)構(gòu)特性，加熱和冷卻的控制儀表特性、機頭特性及裝配情況等，以便正確地掌握擠出工藝條件，正確地操作機器
7.控制系統(tǒng)
塑料擠出機的控制系統(tǒng)包括加熱系統(tǒng)、冷卻系統(tǒng)及工藝參數(shù)測量系統(tǒng)，主要由電器、儀表和執(zhí)行機構(gòu)（即控制屏和操作臺）組成。其主要作用是：控制和調(diào)節(jié)主輔機的拖動電機，輸出符合工藝要求的轉(zhuǎn)速和功率，并能使主輔機協(xié)調(diào)工作；檢測和調(diào)節(jié)擠塑機中塑料的溫度、壓力、流量；實現(xiàn)對整個機組的控制或自動控制。
擠出機組的電氣控制大致分為傳動控制和溫度控制兩大部分，實現(xiàn)對擠塑工藝包括溫度、壓力、螺桿轉(zhuǎn)數(shù)、螺桿冷卻、機筒冷卻、制品冷卻和外徑的控制，以及牽引速度、整齊排線和保證收線盤上從空盤到滿盤的恒張力收線控制。
1. 擠塑機主機的溫度控制
電線電纜絕緣和護套的塑料擠出是根據(jù)熱塑性塑料變形特性，使之處于粘流態(tài)進行的。除了要求螺桿和機筒外部加熱，傳到塑料使之融化擠出，還要考慮螺桿擠出塑料時其本身的發(fā)熱，因此要求主機的溫度應(yīng)從整體來考慮，既要考慮加熱器加熱的開與關(guān)，又要考慮螺桿的擠出熱量外溢的因素予以冷卻，要有有效的冷卻設(shè)施。并要求正確合理的確定測量元件熱電偶的位置和安裝方法，能從控溫儀表讀數(shù)準確反映主機各段的實際溫度。以及要求溫控儀表的精度與系統(tǒng)配合好，使整個主機溫度控制系統(tǒng)的波動穩(wěn)定度達到各種塑料的擠出溫度的要求。
2. 擠塑機的壓力控制
為了反映機頭的擠出情況，需要檢測擠出時的機頭壓力，由于國產(chǎn)擠塑機沒有機頭壓力傳感器，一般是對螺桿擠出后推力的測量替代機頭壓力的測量，螺桿負荷表（電流表或電壓表）能正確反映擠出壓力的大小。擠出壓力的波動，也是引起擠出質(zhì)量不穩(wěn)的重要因素之一，擠出壓力的波動與擠出溫度、冷卻裝置的使用，連續(xù)運轉(zhuǎn)時間的長短等因素密切相關(guān)。當發(fā)生異?，F(xiàn)象時，能排除的迅速排除，必須重新組織生產(chǎn)的則應(yīng)果斷停機，不但可以避免廢品的增多，更能預(yù)防事故的發(fā)生。通過檢測的壓力表讀數(shù)，就可以知道塑料在擠出時的壓力狀態(tài)，一般取后推力極限值報警控制。
3. 螺桿轉(zhuǎn)速的控制
螺桿轉(zhuǎn)速的調(diào)節(jié)與穩(wěn)定是主機傳動的重要工藝要求之一。螺桿轉(zhuǎn)速直接決定出膠量和擠出速度，正常生產(chǎn)總希望盡可能實現(xiàn)最高轉(zhuǎn)速及實現(xiàn)高產(chǎn)，對擠塑機要求螺桿轉(zhuǎn)速從起動到所需工作轉(zhuǎn)速時，可供使用的調(diào)速范圍要大。而且對轉(zhuǎn)速的穩(wěn)定性要求高，因為轉(zhuǎn)速的波動將導(dǎo)致擠出量的波動，影響擠出質(zhì)量，所以在牽引線速度沒有變化情況下，就會造成線纜外徑的變化。同理如牽引裝置線速波動大也會造成線纜外徑的變化，螺桿和牽引線速度可通過操作臺上相應(yīng)儀表反映出來，擠出時應(yīng)密切觀察，確保優(yōu)質(zhì)高產(chǎn)。
4. 外徑的控制如上所述為了保證制品線纜外徑的尺寸，除要求控制線芯（纜芯）的尺寸公差外，在擠出溫度、螺桿轉(zhuǎn)速、牽引裝置線速度等方面應(yīng)有所控制保證，而外徑的測量控制則綜合反映上述控制的精度和水平。在擠塑機組設(shè)備中，特別是高速擠塑生產(chǎn)線上，應(yīng)配用在線外徑檢測儀，隨時對線纜外徑進行檢測，并且將超差信號反饋以調(diào)整牽引或螺桿的轉(zhuǎn)速，糾正外徑超差。
5. 收卷要求的張力控制
為了保證不同線速下的收線，從空盤到滿盤工作的恒張力要求，希望收排線裝置有貯線張力調(diào)整機構(gòu)，或在電氣上考慮恒線速度系統(tǒng)和恒張力系統(tǒng)的收卷等等。
6. 整機的電氣自動化控制
這是實現(xiàn)高速擠出生產(chǎn)線應(yīng)具備的工藝控制要求，主要是：開機溫度聯(lián)鎖；工作壓力保護與聯(lián)鎖；擠出、牽引兩大部件傳動的比例同步控制；收線與牽引的同步控制；外徑在線檢測與反饋控制；根據(jù)各種不同需要組成部件的單機與整機跟蹤的控制。
9
收藏