【導(dǎo)讀】的控制系統(tǒng)提出了很高的要求。隨著電子技術(shù)的不斷進(jìn)步和發(fā)展，此傳統(tǒng)。采用有觸點(diǎn)的開關(guān)動作，工作頻率低，可靠性差，易出故障。繼電器動作慢，定時(shí)不準(zhǔn)確，系統(tǒng)控制精度差等。因而，對注塑機(jī)的控制。系統(tǒng)進(jìn)行改造很有研究必要。文章對注塑機(jī)結(jié)構(gòu)進(jìn)行分析，并進(jìn)對西門子。S7-200PLC的編程方法以及使用的方法進(jìn)行簡單介紹。通過組態(tài)軟件的仿。音、鎖模力容易控制、運(yùn)行平穩(wěn)、安全可靠和便于維修的目標(biāo)！

　　

【正文】 京：機(jī)械工業(yè)出版社 ,2020 [8] 王庭有 .可編程控制器原理及應(yīng)用 .北京：國防工業(yè)出版社 ,2020 [9] 宮淑貞 .可編程控制器原理及應(yīng)用 ( 第一版 ).北京：人民郵電出版社 ,2020 [10] 左健民 .液壓與氣壓傳動 .北京：機(jī)械工業(yè)出版社 ,2020 [11] 張靜章 .簡析注射機(jī)的現(xiàn)狀和發(fā)展策略 . 中國塑料工業(yè)機(jī)械信息 ,2020 [12] 王興天 .注射技術(shù)與注射機(jī) ,化學(xué)工業(yè)出版社 ,2020 [13] 吳建強(qiáng)，姜三勇 .可編程控制器原理及應(yīng)用 .哈爾濱工業(yè)大學(xué)出版社 ,2020 [14] 吳中俊 ,黃永紅 .可編程序控制器原理及應(yīng)用 .北京 :機(jī)械工業(yè)出版社 ,2020 [15] 黃凈 .電氣控制與可編程序控制器．機(jī)械工業(yè)出版社 ,2020 [16] 王永華．現(xiàn)代電氣控制及 PLC 應(yīng)用技術(shù)．北京航空航天大學(xué)出版社 ,2020 [17] 王永華 .現(xiàn)代電氣控制及 PLC 應(yīng)用技術(shù) .北京 :北京航空航天大學(xué)出版社 ,2020 [18] 周美蘭 ,周封 .PLC 電氣控制與組態(tài)設(shè)計(jì) .北京 :科學(xué)出版社 ,2020 外文資料翻譯 Nature works hard to destroy bearings, but their chances of survi val can be improved by following a few simple guidelines. Extreme neglect in a bearing leads to overheating and possibly seizure or, at worst, an explosion. But even a failed bearing leaves clues as to what went wrong. After a little detective work, action can be taken to avoid a repeat performance. Bearings fail for a number of reasons， but the most mon are misapplication，contamination ， improper lubricant ， shipping or handling damage ， and misalignment. The problem is often not difficult to diagnose because a failed bearing usually leaves telltale signs about what went wrong． However， while a postmortem yields good information， it is better to avoid the process altogether by specifying the bearing correctly in The first place． To do this， it is useful to review the manufacturers sizing guidelines and operating characteristics for the selected bearing. Equally critical is a study of requirements for noise, torque, and runout, as well as possible exposure to contaminants, hostile liquids, and temperature extremes. This can provide further clues as to whether a bearing is right for a job. 1 .Why bearings fail About 40% of ball bearing failures are caused by contamination from dust, dirt, shavings, and corrosion. Contamination also causes torque and noise problems, and is often the result of improper handling or the application environment． Fortunately, a bearing failure caused by environment or handling contamination is preventable， and a simple visual examination can easily identify the cause． Conducting a postmortem il1ustrates what to look for on a failed or failing bearing． Then， understanding the mechanism behind the failure, such as brinelling or fatigue, helps eliminate the source of the problem. Brinelling is one type of bearing failure easily avoided by proper hand ing and assembly. It is characterized by indentations in the bearing raceway caused by shock loading－ such as when a bearing is droppedor incorrect assembly. Brinelling usually occurs when loads exceed the material yield point(350,000 psi in SAE 52100 chrome steel)． It may also be caused by improper assembly, Which places a load across the races． Raceway dents also produce noise， vibration， and increased torque. A similar defect is a pattern of elliptical dents caused by balls vibrating between raceways while the bearing is not turning． This problem is called false brinelling. It occurs on equipment in transit or that vibrates when not in operation. In addition, debris created by false brinelling acts like an abrasive, further contaminating the bearing. Unlike brinelling, false binelling is often indicated by a reddish color from fretting corrosion in the lubricant. False brinelling is prevented by eliminating vibration sources and keeping the bearing well lubricated. Isolation pads on the equipment or a separate foundation may be required to reduce environmental vibration. Also a light preload on the bearing helps keep the balls and raceway in tight contact. Preloading also helps prevent false brinelling during transit. Seizures can be caused by a lack of internal clearance, improper lubrication, or excessive loading. Before seizing, excessive, friction and heat softens the bearing steel. Overheated bearings often change color， usually to blueblack or straw colored． Friction also causes stress in the retainer， which can break and hasten bearing failure． Premature material fatigue is caused by a high load or excessive preload． When these conditions are unavoidable， bearing life should be carefully calculated so that a maintenance scheme can be worked out． Another solution for fighting premature fatigue is changing material． When standard bearing materials， such as 440C or SAE 52100， do not guarantee sufficient life， specialty materials can be remended. In addition， when the problem is traced back to excessive loading， a higher capacity bearing or different configuration may be used． Creep is less mon than premature fatigue． In bearings． it is caused by excessive clearance between bore and shaft that allows the bore to rotate on the shaft ． Creep can be expensive because it causes damage to other ponents in addition to the bearing． 0ther more likely creep indicators are scratches ， scuff marks ， or discoloration to shaft and bore． To prevent creep damage， the bearing housing and shaft fittings should be visually checked． Misalignment is related to creep in that it is mounting related． If races are misaligned or cocked． The balls track in a noncircumferencial path． The problem is incorrect mounting or tolerancing， or insufficient squareness of the bearing mounting site． Misalignment of more than 1/4can cause an early failure． Contaminated lubricant is often more difficult to detect than misalignment or creep ． Contamination shows as premature wear ． Solid contaminants bee an abrasive in the lubricant． In addition。 insufficient lubrication between ball and retainer wears and weakens the retainer． In this situation， lubrication is critical if the retainer is a fully machined type． Ribbon or crown retainers， in contrast， allow lubricants to more easily reach all surfaces． Rust is a form of moisture contamination and often indicates the wrong materi