多功能試驗臺的設計【說明書+CAD+SOLIDWORKS】
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編號
無錫太湖學院
畢業(yè)設計（論文）
相關資料
題目：同向旋轉型雙螺桿擠壓機
及傳動系統(tǒng)設計
信機 系 機械工程及自動化專業(yè)
學 號： 0923231
學生姓名： 曹彬彬
指導教師： 戴 寧（職稱：副教授 ）
（職稱： ）
2013年5月25日
目 錄
一、畢業(yè)設計（論文）開題報告
二、畢業(yè)設計（論文）外文資料翻譯及原文
三、學生“畢業(yè)論文（論文）計劃、進度、檢查及落實表”
四、實習鑒定表
編號
無錫太湖學院
畢業(yè)設計（論文）
開題報告
題目：同向旋轉型雙螺桿擠壓機
及傳動系統(tǒng)設計
信機 系 機械工程及自動化專業(yè)
學 號： 09232231
學生姓名： 曹彬彬
指導教師： 戴 寧（職稱：副教授 ）
（職稱： ）
2012年11月25日
課題來源
自擬課題
科學依據（包括課題的科學意義；國內外研究概況、水平和發(fā)展趨勢；應用前景等）
（1）課題科學意義
擠壓加工技術作為一種經濟實用的新型加工方法廣泛應用于食品生產中，并得到迅速發(fā)展。采用擠壓技術來加工食品，只要簡單地更換擠壓模具，便可以很方便地改變產品造型。
擠壓研究內容包括原料經擠壓后微觀結構及物理化學性質的變化，擠壓性能及原料本身特性對產品質量的影響等，為擠壓技術在新領域的開發(fā)應用奠定了基礎。擠壓機有多種機型，本文主要研究螺桿擠壓機，它主要由一個機筒和可在機筒內旋轉的螺桿等部件組成。
螺桿擠壓機按螺桿數量分為單螺桿擠壓機和雙螺桿擠壓機兩大類。單螺桿與雙螺桿擠壓機的主要差別是其中物料的允許水分范圍以及加工能力的差別應是最值得注意的方面。本文主要研究雙螺桿擠壓機。雙螺桿擠壓機是多螺桿擠壓機中的一種，是在單螺桿擠壓機的基礎上發(fā)展起來的。在雙螺桿擠壓機的機筒中，并排安放兩根螺桿，故稱雙螺桿擠壓機。
雙螺桿擠壓機按螺桿方向不同，可分為同向旋轉和反向旋轉兩大類，本文主要研究同向雙螺桿擠壓機。同向旋轉相較反向旋轉，其優(yōu)越性是很明顯的，但這并非說同向旋轉不存在問題。首先是推送效率問題，反向旋轉式螺桿的擠壓建立在類似于齒輪泵的原理上，物料在雙螺桿內的流動不是由于摩擦牽引作用，而是因為機械的強制推送，物料能均勻分配給兩螺桿，所以推送效率高。但雙螺桿同向旋轉式，按螺桿旋轉方向，物料只送往螺桿轉向端，物料分布偏向一方，其推送性只及反向旋轉的一半左右。
（2）擠壓機的研究狀況及其發(fā)展前景
與傳統(tǒng)生產工藝相比，擠壓加工極大地改善了谷物食品的加工工藝，縮短了工藝過程，豐富了谷物食品的花色品種，降低了產品的生產費用，減少了占地面積，大大降低了勞動強度，同時也改善了產品的組織狀態(tài)和口感，提高了產品質量。
隨著人民生活水平的提高和飲食結構的變化，隨著對擠壓機理研究的不斷深入和新型擠壓設備的研制開發(fā)，擠壓食品的品種和產量將會日益增多，并朝著高效節(jié)能，產品風味多樣化和美味化方向發(fā)展。
與發(fā)達國家相比，我國在雙螺桿擠出機的設計制造及應用方面存在很大的差距。國內雙螺桿擠出機開發(fā)及研究工作起步較晚，因此產品檔次較低，系列化程度低，多數產品的技術水平、螺桿、機筒的精度、整機性能和質量與目前發(fā)達國家的發(fā)展水平有一定差距。目前，我國生產的異向旋轉雙螺軒擠出機多為錐形雙螺桿擠出機，平行異向雙螺桿擠出機很少，并且多為中、小型機，國內所需的大型異向雙螺桿擠出機幾乎全部依賴進口。在雙螺桿擠出機的設計、計算以及制造技術方面仍有不少難點需要克服，這些都制約了我國雙螺桿擠出技術與裝備的發(fā)展。
隨著國民經濟的發(fā)展，大型塑料管材、型材、板材在石化、建筑、農業(yè)、國防等領域的應用日漸廣泛。大型平行異向雙螺桿擠出機的開發(fā)研制必將受到越來越多的重視。
研究內容
1.熟練掌握同向旋轉型雙螺桿擠壓機的工作原理與結構
2.熟悉同向旋轉型雙螺桿擠壓機擠壓過程中的螺桿結構設計與受力分析
3.熟練掌握同向旋轉型雙螺桿擠壓機的各參數的設計和各傳動的結構設計
擬采取的研究方法、技術路線、實驗方案及可行性分析
研究方法：
根據課題所確定的擠壓機種類，用途及生產能力確定擠壓機的主要構件（例如螺桿，機筒）機構形式和尺寸參數，運動參數及動力參數（電機功率）。
根據擠壓機主要構件的形式，性質及運動參數，擬定整機的機械傳動鏈和傳動系統(tǒng)圖。計算并確定各級傳動的傳動比，皮帶轉動，齒輪轉動等傳動構件的結構參數及尺寸，擬定機器的結構方案圖。
根據結構方案圖，在正式圖紙上擬定傳動構件及執(zhí)行構件的位置，然后依次進行執(zhí)行構件及傳動系統(tǒng)設計機體，操縱機構設計，密封及潤滑的結構設計。
研究計劃及預期成果
研究計劃：
2012年10月12日-2012年12月31日：按照任務書要求查閱論文相關參考資料，完
成畢業(yè)設計開題報告書。
2013年1月1日-2013年1月27日：學習并翻譯一篇與畢業(yè)設計相關的英文材料。
2013年1月28日-2013年3月3日：畢業(yè)實習。
2013年3月4日-2013年3月17日：單軸式和面機的主要參數計算與確定。
2013年3月18日-2013年4月14日：單軸式和面機總體結構設計。
2013年4月15日-2013年4月28日：部件圖和零件圖設計。
2013年4月29日-2013年5月21日：畢業(yè)論文撰寫和修改工作。
預期成果：
根據提供的主要構件參數而計算出的傳動構件的參數，尺寸及機體等是合理的，可以進行正常的生產組裝，最終達到和面機的工作要求。
特色或創(chuàng)新之處
傳動緊湊、布置合理、方便裝拆。
已具備的條件和尚需解決的問題
1、設計方案思路已經非常明確，已經具備使用CAD制圖的能力和了解同向旋轉型雙螺桿擠壓機原理結構等知識。
2、使用CAD制圖能力尚需加強，結構設計能力尚需加強。
指導教師意見
指導教師簽名：
年 月 日
教研室（學科組、研究所）意見
教研室主任簽名：
年 月 日
系意見
主管領導簽名：
年 月 日
Mixing cases and model experiments
Food or biological macromolecules, unlike chemical polymer, most components including carbohydrates, esters, fiber and water. In principle, each type of food materials is a unique product and its viscosity. This means "mix of food ingredients fully" is difficult to design it also means that every successful design is one kind of tailor made products or models. In experimental method in the past ten years have solved many particles for T.S.E and S.S.E food ingredients. These specific instances of mixed tells us that improve mixing can create a better and more homogeneous products. This is research die fast mixing elements impact on the model experiment to explore how to better understand their ability to mix.
3.1. Case of sucrose-crystal melting (s.s.e.)
Traditional candy industrial water at pre-set temperature dissolved sucrose crystal particles [6]. The melt in the mold cost a lot of time and energy in the dehydration. Sugar in this case the water in the base diffusion rate is very low, so very slow evaporation. It will also attract we developed a new evaporation method to make the moisture content of raw materials down to close to the final product, for this process to design a new screw mixing extruder [27]. In this case the most economical S.S.E extruder design is out of the feeding of sucrose crystal particles beyond the design scheme of any excess water.
3.1.1. Experimental
Used for melting dry sugar solid particles of double screw extrusion machine foundation design, this design can complete melting know no scattered crystals. Battenfeld single-screw extruder (D = 50 * 103 m, L/D = 12, wall thickness = 4 mm, the screw compression ratio = 3, speed = 80) of sucrose solids spray drying, a mixture of sucrose and glucose particles (1:1) to deal with both copper and cobalt thermocouple measuring temperature distribution, the distribution is a kind of microcosmic evaluation, using distance measuring input power, according to the international camel value comparison method measuring the quality and per color。
3.1.2. Results and discussion
Phenomenon, the limitations of the sucrose crystal melting during which exists in the two-thirds of spiral level, sucrose crystals have not mixed with other things here, this kind of phenomenon in each uninterrupted have existed in the single screw extruder, heat transfer of cylinder is poorer, therefore, that means time-consuming melting process cannot be mixed element allocation in material extrusion in the choice, in this case the so-called extrusion die head provides a solution. So-called the mixed function of extrusion die head is distribution of flow, and the remaining solid crystals scattered in the thermal boundary layer on the surface of the cylinder body, solid crystal will slowly melt in thermal boundary layer. Now realize a lot of scattered melt is achievable, but the L/D ratio is increased from 12 to 16, even if the emergence of the melt
will prevent extrusion machine's push in the materials. S.S.E. throughput is placed in a carefully crafted solid feed area decided to [7], this design let feed only by through the clearance of screw and barrel.
Figure 7 shows the step by step development of work from start to end to the process of melting and melt temperature distribution measurement.
3.2. Case of breakfast cereal production (counter-rotating t.s.e.)
Used in the production of breakfast cereals, rotate T.S.E. is a very attractive a piece of equipment that work in such a manner due to its low shear force to ensure the integrity of the starch particle, they have good water absorption performance after heat treatment. So it is necessary to execute element rather than the distribution of the dispersed elements of hybrid, this is referred to in section 2.3 in T.S.E mixture can provoke slotted screw design, when rotating T.S.E. slotted screw production breakfast cereal, the flow of food particles between the adjacent screw a bolt and forced mixing and flow.
3.2.1. Experimental
Extruder is using a tapered rotary extruding machine by the Cincinnati Milacron create 45 type (CMA), breakfast cereal and the ideal height of cold paste viscosity (CPV) manufactured by coarse flour as a substitute for traditional drum - dry product.
Fig. 7. Start and final result of a multiple step s.s.e.-development for melting of sucroserglucose mixtures.
Machine use average L/D 15 eight holes, mold material is 4 mm in diameter, on the water content of 25% feed capacity is
100 kg/h of material during production we need screw vice speed of 80 r/min. Groove of screw three lengths (L1, L2, L3) in the position of the second paragraph structure into three screws. Paragraphs length L1 (2 x 55 mm), L2, L3 (2 x 110 mm), (2) x 165 mm. Product sample and the design of the screw is used to determine the viscosity on cold paste and hot. High CPV can provide better breakfast cereals "scoop capacity", namely has good adhesiveness. To represent viscosity data using the so-called temperature - time driven brunton viscometer, and blah unit of measurement.
The limiting phenomenon during melting in an s.s.e., is the existence of a stationary layer at 2r3 of the screw
channel height ?related to the screw root , where sucrose. crystals remain present without additional mixing. This is a
property of each single screw extruder provided with a non-interrupted screw channel. The heat penetration rate
from the barrel is low, due to this phenomenon, which means that the time consuming melting process can not be
performed in the available residence time. The selection of a distributive mixing element, in this case a so-called
pineapple head, gave the solution. The mixing function of the so-called pineapple head is to distribute the flow and to
bring the remaining solid seeding crystals to the hot boundary layer at the inner surface of the barrel, where
they will melt.
3.2.2. Results and discussion
3.2.2.1 Flow phenomenon
Between kneading paddle and inversion element has an obvious difference in motion, in all investigation the set point of
stagnation due to reverse course elements to be noticed. Can clearly see the tracer particles before further axial transport time is on irregular movement. This is conducted in the absence of kneading paddle, mixed in the setting of stagnation point there is not enough, for the first kneading paddle flow effect we give a diagram (figure 11)
In extrusion, mixing of solids and melts has always been problematic, leading to diverse models describing the melting process. It is found that for foods based on cereals, only a few are valid, due to the simultaneous presence of water and high viscous non-Newtonian material. Mixing trials are summarised for single and twin screw extruders, with particulate solids of different particle sizes like, maizegrits, wheat flour, sucrose crystals and glucose syrup. Special mixing-heads for single screw extruders like, pineapple-heads, and slotted flight sections for counter-rotating twin screw extruders are investigated. The effects of screw geometry on mixing has been measured using co-rotating twin screw extruder modular elements like: single lead elements, mixing paddles and reversed pitch elements in a translucent model extruder by means of a study of flow phenomena and residence time distribution RTD measurements. Mixing effects are reported and their influences on viscous dissipation, residence time, curve spread and stagnancy are explained. 1999 Elsevier Science S.A. All rights reserved.
When food particles during their lifetime in an extruder are subjected to axial mixing, this can be seen and measured by a changing RTD. Extremes in this case are plug flow, where all particles have the same residence time, or a wide RTD which is caused by axial mixing. Some particles will stay in the extruder cooker for a process time shorter than the average, whilst others will dwell for much longer than the average when different flow systems are compiled see Fig. 2 . Fig. 3 shows the theoretical RTD for a material with a coefficient ns1 in the power-law equation for the shear dependency of the viscosity in an s.s.e.This figure also shows the RTD data, measured when
processing corn grits in a Battenfeld s.s.e. at two moisture y1 . contents v s0.142, 0.20 kg kg and screw revolu- w y1 wx tions
ranging from Ns1.33, 1.66, 2.0 rev s 22 . The RTD data are represented as an ‘cumulative exit age’ or F-function, which shows the fraction F of the inflow, wx which has left the extruder after t seconds 3,4,16 . The E-function, the derivative of the F-function, shows the so-called ‘exit age’ distribution of food particles, fed into the extruder at an infinite small time and is related to the F-function with: t Ft s Et dt 1 H 0 The average residence time t of the food material in the cooking extruder is calculated with: ts tE t dt .2 H When the F-function in Fig. 3 is observed, it follows that most of the corn grits have an exit age between t and t , 0 whereas t (3r4t . These measurements show that for a 0 single screw extruder there is a strong influence of the moisture content and the number of revolutions of the screw on the shape of the F-function and the breakthrough wx point 3 .The operating principle of twin screw extruders can be described with the existence of two parallel series of Continuously Stirred Tank Reactors CSTR , where each wx C-shaped chamber represents such a CSTR 13 .
Independent thread element and before the viscosity and speed of measurement on the low pressure side of the blade, figure 11 when the situation is on the first flow and spiral around the blade with the blades at the top of the line. Next is on
the high voltage side of low pressure side of the blade flow along the direction of the net flows. According to the viscosity of the fluid and the speed of the extruder, the screw can even screw in front of the material flow into the channel transmission
part, however, when open in front of the screw channel transmission element is connected to the first blade, rotary will take place in the same way, but the direction of the net will be pushed to the following oar or screw channel open space. According to the velocity profile after several propeller speed gradually slow down, the kneading blade paddle series show the effect is not so clear, and through a long paddle is more like a piece of transportation behavior plug-in flow. Stagnation of kneading paddle place did not appear, because they always keep the components and transport radial vortex clean. Kneading elements in the screw conveyor has limited effectiveness, the need to push the material through the screw kneading in front of the part of the spacing. Although no significant stagnation were observed in the block adjustment and reverse blades by increasing the Angle between a small difference. Therefore mixed in kneading and delivery of material in the axial T.S.E is small. We should consider these so-called pressure, provide some mild mix. Observed due to the action on the paddle, the axial mixing seems to be several separate extrusion machines for about 4-6 OARS OARS block has the same total length, rather than a long paddle block inside the screw is more effective.
3.3.2.2. Residence time distribution.
These trials with different viscosity and speed setting control quantity. RTD qualitative impact of similar results. In figure 12 and 13, E, F curve shows that the viscosity of 30 pas material in a mixed stirring in touch, and under the high speed extrusion (60 RPM). For the following this example and analysis the result of the discussion, because the influence of the mixed section here is one of the most obvious, is all have survey gave similar results.
Based on RTD measurement analysis, each data is calculated by Eq, the average residence time (?) the width of the curve using t84 / t16 presented here as a parameter, CSTR (N *) calculation and calculation of Peclet number (Pe)
Quantitative amount for such axial mixing. Parameters describing the database (t92 / T), can be seen as stagnation of measure a screw installed. Variance (sigma 2) is a statistical parameters and can change in an instant, as a measure of the quality problem.
Fig. 12. Effect of mixing sections on the E-curve in a co-rotating t.s.e. h s 30 Pa s, 60 rpm .
For a given example of calculation parameters are shown in table 1.
Table 1 shows the data of the width of the curve analysis process, direct coupling Peclet number and the number of CSTR shows good correlation (N *). PE also represents the very good agreement of design information equipment design and user part of the composition of the industry. To evaluate the mixing effect, the use of a single screw element as a reference. We can from figure 12 and figure 13, in table 1 using a 90 - degree blade make average residence time of no significant change, but the width of the curve has a clear and tail. The width of the curve and tail has been reduced, which reduce the stagnation of the plug flow increases. This also proves that we need to calculate N * and PE. The OARS reverse 30 degrees, thus increasing the average residence time and increase the width and length of the tail curve. Suggesting that block the flow can increase the axial mixing, prove, N * and Pe.
Fig. 13. Effect of mixing sections on the F-curve in a co-rotating t.s.e. h s 30 Pa s, 60 rpm .
Figure 12 shows that N * and Pe number compared with the reverse 30 degrees can, greatly increase the average residence time and increase the width of the curve. However, the analysis of the data does not show the growth curve of width. Compared with other elements of the research, the curve showed his early research value. Axial forward this effect shows that the so-called "hybrid" because of the flow phenomenon occurred in the thread and the velocity profile.
Kneading paddle (90 °) can provide perfect limited radial mixing and axial mixing, because they are conveying screw in front of power consumption component so you need to provide power. Blade positioning, relative to the normal condition can reduce the flow and pressure. The axial mixing, can increase the number of placed upside down the oar, and stagnation phenomenon is still exist. Single screw structure can provide good conveying capability, but isn't particular good mixed ability. But we have to make OARS of the screw, because they can provide the necessary delivery pressure.
Inversion of the active screw and screw kneading paddle, conveying the reversal of the screw part of the need to overcome negative suction effect. This explains the synchronization effect early breakthrough and stagnation. As the first part, in the
case of most of the food raw material, the effect will be lower the viscosity of the product portfolio and screw elements on the product on the total amount of shear. These changes will affect the axial mixing degree of viscosity. The axial mixing ability, depends on the gap between screw and barrel number and size.
In previous research, and has summed up the various authors of all types of food raw material extrusion using a twin screw extruder. All these documents will affect the RTD appearance changes, the curve of T.S.E. diffusion and viscous dissipation are stagnant. In the overall conclusion that these files are in table 2 as a qualitative result summary.
The conventional confectionery industry uses water to dissolve particulate sucrose crystals at pre-set temperatures
w6 . The melt is casted in cornstarch moulds and the excessx water is removed with careful and time and energy con-
suming drying operations. In this case the low diffusivity of water in sugar-based solid products is responsible for a
low-drying rate. It is more attractive to develop a cooking method with initial water contents as close as possible to
the end-product moisture content. For this process an appropriate extruder and mixing screw had to be designed
w27 . In this case the most economical extruder design is anx s.s.e. directly fed with sucrose crystals as particulate solids
without any addition of extra water.
For the production of breakfast cereals, a counter-rotat-ing t.s.e. is an attractive piece of equipment due to its low
shear level guarantying the survival of starch particles in such a way that they have kept there good
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