2014年11月2日星期日
Plastic bearing-Self-Lubricating Sliding Bearings
Bearings are useslide bearingd as a mechanical component to transfer the power and to move a certain part, and this is done by utilizing the small frictional force of the bearings, which makes them rotate easily。 Bearing products can be further divided into various types according to different classification methods。 When depending on friction type, they can be classified into two major groups, namely, sliding bearings and rolling bearings。
Sliding bearing can represent both the hydrodynamic lubrication bearings requiring lubricants that automatically form the oil film in the space between shaft A and bearing B by way of rotating the shaft and the hydrostatic lubrication bearings requiring lubricants that elevates the rotating shaft by providing the pressurized lubricant from outside。
Besides, they can also represent both the self-lubricating bearings made of special material that requires no lubricants between shaft A and bearing B and the ones made of porous material to be soaked with lubricants。 Now let us talk something about the self-lubricating sliding bearings。
With the development of the technology, there are more and more requirements for the performance of the bearings。 Even zero maintenance is expected under severe to extreme conditions as well as under maximum loads。 The constant pressure on costs additionally calls for increasing uptime of machinery and equipment and uncompromising standards of operational reliability。
Maintenance-free, self-lubricating, heavy duty friction materials produced for bearings of the automotive industry offers bearing solutions guaranteed to operate reliably and safely over long term。 Therefore, the self-lubricating sliding bearings are manufactured to meet special requirements。
Self-lubricating composite sliding material manufactured by using a continuous hot rolling sintering technology which increases the reliability and service lifetime of the sliding plates significantly。 It is characterized by high wear resistance, insensitive to impact stress and resistant to harsh operational and ambient conditions of mechanical and chemical environment。
It normally requires no lubrication and allows maintenance free。 It is suitablePlastic bearing for rotational, oscillating and linear movements。 These materials can be machined to complex geometrical shapes without the loss of the self-lubricating properties。 In addition, they possess a high static and dynamic load bearing capacity。 These bearing materials contribute to enhance performance and optimum characteristics in all industrial segments。 The dry wear mechanism enables these bearings to operate satisfactorily in the absence of conventional lubricants。
powder metal-Metal Injection Molding
What is Metal Inpowder metaljection Molding?
Metal injection molding is a powder metallurgy process used for manufacturing metal parts。 Although metal injection molding uses , it is nothing like conventional powder metal processing。 The metal powders used in metal injection molding are 10-100 times smaller than in powder metal processes。 Also, the end product of metal injection molding is much higher in density。 Metal injection molding offers the same benefits and features as plastic and rubber molding, but produces a much stronger end product。 Applications for metal injection molding parts include surgical tools, automotive locks and actuators, firearm components, computer hard disk drives and electrical connectors。
Process of Metal Injection Molding
Metal injection molding is a fast growing manufacturing method that bridges the gap between the technology up gradation and costs involved。 The metal injection molding process involves five steps, mixing, injection molding, de binding, sintering, and part finishing。
In the mixing step, metallic powders, selected for their strengths and inherent abilities suchsintered metal as impact strength, high and low temperature characteristics, wear resistance characteristics, machine ability, and hardness, are mixed, often with a binding agent。 By mixing powders, the goal is to create a composite with the strengths and benefits of all the incorporated metals, while offsetting the independent weaknesses。
Once the powders are mixed, a "feedstock" is produced。 This feedstock is injected into molds in the same way that plastic or rubber injection molding is performed。 The part that emerges from the injection molding stage is referred to as a "green" part。
In the de binding stage of metal injection molding, the green part is immersed in a water bath to remove the binder, which has entered into the part matrix。 In cross-linking, the de bound green part is exposed to ultraviolet light which thermo sets the binding agents used with the metal powders。
Once the de binding stage has been completed, the part is placed into a furnace and heated to over 2000 degree Fahrenheit。 This process, called sintering, fuses the metal parts into a solid shape。 Finally, the sintered piece is sent to a finished stage where burrs and surface imperfections are removed and the finished part can besintered metal shipped。
Advantages of Metal Injection Molding
- High Shape Complexity
- Low Cost
- Tight Tolerances
- High Density
- High Performance
Uses of Metal Injection Molding
The technology excels at applications that require shape complexity and high final properties, such as high strength and density, excellent magnetic permeability, high temperature strength, corrosion resistance, and thermal conductivity in applications that cannot be fulfilled by plastics or light metal alloys。 Metal injection molding is thus best for some of the following uses viz。 making of microelectronic packaging, automotive sensors and actuators, hand tools and hardware, computer heat dissipation devices, oil well drilling tools, aerospace and engine fuel components。
To Sum Up
Metal injection molding can provide a substantial cost savings over conventional metal machining options。 Metal injection molding parts have high densities and mechanical properties approaching those of forged or machined components。 Metal injection molding process can produce more complex parts than either investment casting or traditional press and sinter techniques。
Metal injection molding is a powder metallurgy process used for manufacturing metal parts。 Although metal injection molding uses , it is nothing like conventional powder metal processing。 The metal powders used in metal injection molding are 10-100 times smaller than in powder metal processes。 Also, the end product of metal injection molding is much higher in density。 Metal injection molding offers the same benefits and features as plastic and rubber molding, but produces a much stronger end product。 Applications for metal injection molding parts include surgical tools, automotive locks and actuators, firearm components, computer hard disk drives and electrical connectors。
Process of Metal Injection Molding
Metal injection molding is a fast growing manufacturing method that bridges the gap between the technology up gradation and costs involved。 The metal injection molding process involves five steps, mixing, injection molding, de binding, sintering, and part finishing。
In the mixing step, metallic powders, selected for their strengths and inherent abilities suchsintered metal as impact strength, high and low temperature characteristics, wear resistance characteristics, machine ability, and hardness, are mixed, often with a binding agent。 By mixing powders, the goal is to create a composite with the strengths and benefits of all the incorporated metals, while offsetting the independent weaknesses。
Once the powders are mixed, a "feedstock" is produced。 This feedstock is injected into molds in the same way that plastic or rubber injection molding is performed。 The part that emerges from the injection molding stage is referred to as a "green" part。
In the de binding stage of metal injection molding, the green part is immersed in a water bath to remove the binder, which has entered into the part matrix。 In cross-linking, the de bound green part is exposed to ultraviolet light which thermo sets the binding agents used with the metal powders。
Once the de binding stage has been completed, the part is placed into a furnace and heated to over 2000 degree Fahrenheit。 This process, called sintering, fuses the metal parts into a solid shape。 Finally, the sintered piece is sent to a finished stage where burrs and surface imperfections are removed and the finished part can besintered metal shipped。
Advantages of Metal Injection Molding
- High Shape Complexity
- Low Cost
- Tight Tolerances
- High Density
- High Performance
Uses of Metal Injection Molding
The technology excels at applications that require shape complexity and high final properties, such as high strength and density, excellent magnetic permeability, high temperature strength, corrosion resistance, and thermal conductivity in applications that cannot be fulfilled by plastics or light metal alloys。 Metal injection molding is thus best for some of the following uses viz。 making of microelectronic packaging, automotive sensors and actuators, hand tools and hardware, computer heat dissipation devices, oil well drilling tools, aerospace and engine fuel components。
To Sum Up
Metal injection molding can provide a substantial cost savings over conventional metal machining options。 Metal injection molding parts have high densities and mechanical properties approaching those of forged or machined components。 Metal injection molding process can produce more complex parts than either investment casting or traditional press and sinter techniques。
2014年10月15日星期三
龍眼蜜-蜂蜜的魔力
長時間裏,蜂蜜是人類所知唯一的天龍眼蜜然甜味劑。在人類的遠古記憶中,從人類一出現就開始食用蜂蜜了,並認爲這是神聖的甜味。
古埃及人把蜂蜜當做防腐劑使用,也作爲食物和藥物食用。古埃及人用蜂蜜喂養神聖的動物,各種宗教儀式上也經常用到蜂蜜。古埃及文明認爲蜂蜜非常珍貴,曾經一度成爲貨幣,有很多蜂蜜的人被認爲非常富有。蜜蜂還曾經是法老的象征。在以色列、中國和印度的曆史上,也都有食用蜂蜜的記載,在羅馬帝國,還首次出現了有關蜂蜜制作和蜜蜂飼養的專著。蜂蜜的尊貴多少與甜味讓芋泥捲人愉悅有關。
最初人類食用的蜂蜜大部分都來自野生蜂巢。人類采集野生蜂蜜的記錄最早出現在西班牙比科爾普的洞穴繪畫上,畫中描繪了兩個人順著草編的軟梯去采集懸崖上的蜂巢,這些岩畫創作于公元前數千年前。發現一個野生的蜂巢最開始是出于偶然,但是人們很快發現,雖然蜜蜂不停地從一朵花飛向另一朵花,但是它總是會滿帶著花粉徑直飛回蜂窩,于是“beeline:直線”這個詞就誕生了。
通過跟蹤蜜蜂,蜂蜜獵人總是能找到蜂窩。在殖民地時代的美洲,蜂蜜獵人爲了尋找野生的蜂窩,總是一個人居住在荒野中。一旦發現蜂窩,他便把整棵樹砍倒,把蜂巢裝在桶裏。這是一件危險而孤獨的工作,但是對蜂蜜的需求令它不可或缺。當時蔗糖非常稀少而且昂貴,直到18世紀之前,大多數的歐洲和美洲人只能把蜂蜜當成唯一的甜味劑。在人工馴養蜂群並不普遍的文明中,比如印度,蜂蜜獵人長期存在。在很多印度部落中,蜂蜜醋關于蜂蜜有許多特殊的法律,比如從別人家偷取蜂蜜會被處以死刑。
台中豬腳-一只成爲風景的豬腳
我看那個叫“舌尖”的電視片,發現滷味起名字的聰明,因爲他把舌頭和腸胃,變得有記憶了。這種記憶藏在你內心最深的地方,用那些味蕾感知的世界的味道,連同那美味産生時的風景,都收藏好,等你老了,閑得發呆時,翻腸倒肚地想。
到了東川的橋兒溝,就可以看到寶塔山了。看到了,就算到了。在延安插隊的日子,每月有一天進延安城。進延安城是件快活的事,休息的日子,不想再窩在溝裏。從落戶的曹坪出溝,雞腳凍到公社李渠七八裏。到李渠就到川道了,川比溝寬,溝裏的河叫溪,溪流進了川叫河,川道裏的河叫延河。在川道的公路上再走二十裏,就到了延安。上一次延安來回走六七十裏,圖啥呢?看一回電影?逛一回延安的馬路?還有,還有就是到橋頭那個飯店買一只鹵豬腳。從插隊的小團購美食村子,走到賣鹵豬腳的飯堂櫃台,是一個稍有點漫長的過程。鹵豬腳再加延安,就此就像一個命令符號,打開一串風景……
洗臉、刮胡子、換一身幹淨的衣服。一出窯洞,村頭的婆姨就招呼上了:“延濱喲,今天不出工了呀。”人說這裏婦女地位低,買賣婚姻。然而村上的習俗是女子出嫁前,和男人一樣出工。女子結了婚就是“全職太太”,一個月最多出工5天,其余時間都在家裏管孩子做家務。閑下了身子,閑不住嘴,和知青男孩開玩笑是婆姨們最開心的集體娛樂,用今天的話來形容叫“精神廣場舞”。
逃離婆姨們的笑聲,沿溝底的小台中豬腳路往外走,心情也漸開闊。山峁越走越低,眼前的溝口越走越寬,天藍藍任雲飄,那些雲好像是從心窩口溜出來,看著就親,望一眼就不自禁地咧嘴笑。溝裏的風景就像村莊裏的親戚,簡單得用不光手上的指頭:山峁、水溝、窯洞、青苗、數得過來的幾棵樹、幾條狗、幾只雞,數不過來的是這天上的雲。
路是越走越寬,走到李渠就是公社所在的場鎮了。那時不叫鎮,就叫公社。我們村第一個上調的插隊女知青張桂花,就招到了公社,當了公社廣播員。張桂花長得漂亮,老鄉誇“一笑兩酒窩”。那時真羨慕這女子不用下地幹活,主要是悄悄也喜歡那兩酒窩。
走過了李渠,就是直通延安的大川道。公路沒有鋪柏油,汽車一經過,就揚起一堆塵土。早先還有夢想,招手擋車。後來發現這是最不可能的事情,如像招工一樣,可望而不可即。好在路上車不多,所以,失望的機會也少。一個人走大路,比走小路還寂寞,寂寞就喊,走過村子,啊嗬一聲,回應是汪汪的狗叫。沒狗叫的地方就唱:“我們走在大路上,意氣風發鬥志昂揚……”那年月這歌挺流行,現在回想起來,悟出一點味兒來。
進了城,如果有電影,休管演什麽,也看一場。那時還沒有什麽可看的,連樣板戲都還沒有上電影。電影院裏除了西哈努克,就是阿爾巴尼亞。西哈努克親王不在柬埔寨呆著,《西哈努克訪問西北》《西哈努克訪問東北》,西哈努克的紀錄片,是彩色的;阿員林名產爾巴尼亞的是黑白的。票價都一角錢。就這樣,也不是回回能瞅上。停電,那麽這一天無黑白,更無色彩。
最後的高潮是橋頭飯堂。那年月,飯堂人少,吃飯要糧票,一張大拇指般大的紙片,把饑餓擋在門外。天不絕人。窮得叮當響的陝北,有窮人的窮講究。當時的當地老百姓不愛吃下水和頭蹄。賤得很。橋頭飯店裏賣的鹵豬腳,一只三角錢。除了知青,當地人幾乎無人問津。我懷疑,這滷豬腳也是插隊知青到了這裏以後,這個飯堂的重大新舉措。
遞上三角錢,然後,大師傅用一張黃色的糙紙,包上一只醬紅色油亮並散發香滷味氣的豬腳。接過這只豬腳,我坐在靠窗的長條凳上,望著寶塔山,想起那老電影裏的台詞:“面包會有的,牛奶也會有的,一切都會有的!”手上的豬腳真香,窗外風景如畫。
乾燥機-帶式壓濾脫水機介紹
帶式壓濾脫水機是由上下兩條張汙泥脫水機緊的濾帶夾帶著汙泥層,從一連串有規律排列的輥壓筒中呈S形經過,依靠濾帶本身的張力形乾燥機成對汙泥層的壓榨和剪切力,把汙泥層中的毛細水擠壓出來,獲得含固量較高的泥餅,從而實現汙泥脫水。
一般帶式壓濾脫水機由濾帶、輥壓筒、濾帶張緊系統、濾帶調偏系統、濾帶沖洗系統和濾帶驅動系統構成。作機型選擇時,應從以下幾個方面加以考慮:
(1)濾帶。要求其具有較高的抗固液分離拉強度、耐曲折、耐酸堿、耐溫度變化等特點,同時還應考慮汙泥的具體性質,選擇適合的編織紋理,使濾帶具有良好的透氣性能及對汙泥顆粒的攔截性能。
(2)輥壓筒的調偏系統。一般通過氣動裝置完成。
(3)濾帶的張緊系統。一般也由氣動系統來控污泥乾燥機制。濾帶張力一般控制在0。3-0。7MPa,常用值爲0。5MPa。(4)帶速控制。不同性質的汙泥對帶速的要求各不相同,即對任何一種特定的汙泥都存在一個最佳的帶速控制範圍,在該範圍內,脫水系統既能保證一定的處理能力,又能得到高質量的泥餅。
帶式壓濾脫水機受汙泥負荷波動的影響小,還具有出泥含水率較低且工作穩定啓耗少、管理控制相對簡單、對運轉人員的素質要求不高等特點。同時,由于帶式壓濾脫水機進入國內較早,已有相當數量的廠家可以生産這種設備。在汙水處理工程建設決策時,可以選用帶式壓濾機以降低工程投資。目前,國內新建的汙水處理廠大多采用帶式壓濾脫水機,例如北京高碑店汙水處理廠一期工程五台脫水機全部是帶式壓濾脫水機,自帶、輥壓筒、濾投入運行以來情況良好,所以在二期設備選型時仍然選用了這種機型。
學英文-小學生學英語 如何從“無趣”變“有趣”
如何讓學生盡快適應從小學學英文到中學英語課程的轉變?9月24日上午,南甯市高新區舉行中小學英語教學銜接研討會,130多名中小學英語科任老師及教學副校長聚在一起,希望找出問題答案。
當天,爲讓在座老師對中小學英語教學有更直觀了解,中學老師和小學老師各上了一堂英語展示課。老師們發現,小學老師在課堂上主要是聽、說訓練,課堂形式更活潑,而中學老師在課堂上則對聽、說、讀、寫都有要求,整個課堂都是針對中考題型來展開教學,實效性更強。
接下來的評課階段,中學老師把“矛頭”對准了小學英語教學,認爲小學生英語學習水平參差不齊,導致到初中後對英語學習失去熱情。此外,小學階段沒有音標教學要求,增加了學生在初中英語學習的難度。對此,小學老師則顯得委屈,在小學階段英語只是副科,很多學校每周只安排兩節英語課,並且,小學階段主要是培養學生對英語的興趣,不需要掌握太多詞彙量。
當天,柳州市十五中學英語高級教師韋勝作爲特聘專家,也來到現場。據其介紹,柳州在去年也曾做過一次初中和高中英語教學銜接,初中和小學英語教學銜接的探討會。老師們通過研討發現,初中與小學在教學要求上確實存在脫節。
高新區英語教研室兼職教研員蘇迨吉介紹,該城區很多學英文 補習班生來自農村,學習英語的興趣不濃,進入初中後對英語有興趣的學生不到30%。爲此,今年3月,該城區對中小學英語教學進行了調研,並于6月份讓轄區內的中小學對各校英語教學做總結分析,並計劃集結成書發給學校。此次,他們希望中小學老師們通過研討,找到幫助學生盡快適應小學到初中過渡的切入點。
台北油漆粉刷-減少塗料施工耗損的6方法
1、對新牆體牆面的粉塵異物、台中油漆粉刷裂縫、剝落處等會影響塗刷效果和造成不必要的耗損,所以要先將牆面的所有粉塵異物等刷掉,所有裂縫、剝落處要填縫並整平,同時確保牆體無鹽堿、油膩物及龍脊。開始施工時,台中油漆對相鄰的牆面要作遮擋措施,以免台北油漆工程噴上塗料。
2、舊牆面因爲已經過基礎的處理,要做的就是確保牆體基底牢固。可先用蘇打水溶液沖洗牆面,刷洗幹淨後再用子找平牆面。
3、要節省塗料,施工宜采用刷塗或輥塗的台北油漆方式,而爲了保證封面的平整與光滑,適宜用噴槍噴塗,對不需噴塗的牆面需要預先遮蓋。
4台北油漆粉刷、噴嘴的不同選用,也會影響塗料的耗損程度。采用較小噴幅的槍嘴時其損耗會較低,而且不同品牌台中油漆工程的噴塗工具的噴塗效果不同,對塗料的耗損也有不同。
5、油漆施工的最佳溫度爲5-40度,濕度爲百分之九十以下。春、夏、秋三個季節都較適宜牆面施工。如采用噴塗方式,噴塗時的風速應小于6米每秒,空壓機的供壓應在60牛頓以上。
6、做好施工規劃,安排好施工的時間,如果時間不夠,一味求快,施工人員可能因爲趕進度而采用耗損塗料的方式,而且也不利于裝修質量的保證。如果是業主自己購買塗料,要根據家居的建築面積計算好需要的塗料量。
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