【正文】 等影響，末級(jí)功率放大器電路往往會(huì)失效。（5）與換能器匹配：一是通過匹配使超聲發(fā)生器向換能器輸出額定的電功率，這是由于發(fā)生器需要一個(gè)最佳的負(fù)載才能輸出額定功率所致，把換能器的阻抗變換成最佳負(fù)載，也就是阻抗變換作用。因此在發(fā)生器輸出端并上或串上一個(gè)相反的抗，使發(fā)生器負(fù)載為純電阻，也就是諧調(diào)作用。根據(jù)要求，確定超聲波設(shè)計(jì)參數(shù)：保險(xiǎn)座:在輸出過載或超聲換能器工作異常時(shí)及時(shí)斷開電源，保護(hù)超聲波發(fā)生器。頻率微調(diào):超聲波輸出頻率為28K，但在一定范圍內(nèi)連續(xù)可調(diào)，在不同的工況條件下調(diào)整微調(diào)使換能器始終工作在最佳狀態(tài)下，換能效率達(dá)到最大。掃頻:在清洗過程中使超聲頻率在合理范圍內(nèi)往復(fù)掃動(dòng)，帶動(dòng)清洗液形成細(xì)微回流，使工件污垢在被超聲剝離的同時(shí)迅速帶離工件表面，大大縮短工件清洗時(shí)間，提高清洗效率，以達(dá)到快速清洗的目的。根據(jù)以上要求，綜合考慮選用東莞科美達(dá)公司生產(chǎn)的KMD—300型超聲波發(fā)生器，其規(guī)格為220210100mm，功率為300W，清洗溫度50℃，頻率可調(diào)28Khz 超聲波換能器是一種將機(jī)械能，高頻電能轉(zhuǎn)化為聲能的裝置。換能器一般分成兩個(gè)部分，第一部分是換能器材料部分，第二部分是機(jī)械振動(dòng)放大部分，又叫變幅桿。換能器示意圖如圖54：圖54 超聲波換能器結(jié)構(gòu)示意圖換能器有電動(dòng)式、電磁式、磁致伸縮式、電容式、壓電式等，其中，壓電式因其轉(zhuǎn)換效率高，功率容量大以及結(jié)構(gòu)形狀等可以根據(jù)實(shí)際要求自行設(shè)計(jì)等優(yōu)點(diǎn)而廣泛使用。功率密度可達(dá)900W/1720cm2=。綜上，這里選擇東莞科美達(dá)公司生產(chǎn)的HS—3828型超聲波換能器，其規(guī)格為：5968mm，阻抗≤20Ω，功率為100W，最高可用溫度120℃。 加熱系統(tǒng)在清洗槽底部均勻布置加熱器，在自來水進(jìn)入清洗槽后，控制面板控制加熱器啟動(dòng)，通過實(shí)驗(yàn)測(cè)定加熱器功率加熱到50℃的時(shí)間為4分鐘左右，所有加熱4分鐘后加熱器停止工作。其結(jié)構(gòu)示意圖如圖 圖55 加熱器結(jié)構(gòu)圖 本章小結(jié)結(jié)構(gòu)基本合理，能達(dá)到設(shè)計(jì)要求。第六章編輯控制邏輯圖如下： 圖61 清洗流程圖 處理器選擇根據(jù)邏輯圖選擇PLC控制器，這里選用西門子CPU224其參數(shù)為：100—230V24V繼電器輸出；共24個(gè)數(shù)字量I/O點(diǎn)；最大擴(kuò)展至168路數(shù)字量I/O點(diǎn)或35路模擬量I/O點(diǎn)；６個(gè)獨(dú)立的30KHZ高數(shù)計(jì)數(shù)器；1個(gè)RS485通訊/編程口； 第七章 總 結(jié)本文是以“新型超聲波洗碗機(jī)”課題為研究背景的。而我國(guó)是以碗為主要餐具的國(guó)家，碗具類型、規(guī)格、式樣五花八門，碗的凹度大，且比較油膩。迄今為止，超聲波清洗技術(shù)在家用洗碗機(jī)的應(yīng)用在我國(guó)還屬空白。因此，本課題所作的研究工作具有非常重要的意義?，F(xiàn)把設(shè)計(jì)中具有的優(yōu)點(diǎn)和創(chuàng)新之處總結(jié)如下。同時(shí)，除超聲清洗外，還配備噴臂沖洗，使清洗更加徹底，避免了清洗死角。這是本設(shè)計(jì)最突出的優(yōu)點(diǎn)。采用不銹鋼清洗槽。設(shè)計(jì)缺陷：1. 對(duì)于洗碗過程中的食物殘?jiān)?，雖洗碗機(jī)中設(shè)有過濾裝置，但最終還是需要人工把它拿出，這并不能體現(xiàn)出洗碗機(jī)的全自動(dòng)化。3. 洗滌程序不完善。如果沒有消費(fèi)者的高度認(rèn)同和接受，家用洗碗機(jī)事業(yè)很難發(fā)展，消費(fèi)者期待更便宜的價(jià)格，更節(jié)約的清洗方式，更人性化的操作方式，更符合，更具有中國(guó)特色的家用洗碗機(jī)產(chǎn)品，家用超聲波洗碗機(jī)的出現(xiàn)，無(wú)疑為洗碗機(jī)市場(chǎng)的發(fā)展探索提供了另一種具有前途的方式。另外，在畢業(yè)設(shè)計(jì)寫作過程中，各位同學(xué)也給予了我很大的的幫助，使我感受到了合作和信息共享的重要性。2004（2）.[ 9 ] 周里群，.[10] ，2002(6):7276．北京：機(jī)械工業(yè)出版社：2001[12] 成大先．機(jī)械設(shè)計(jì)手冊(cè)[M]．北京：化學(xué)工業(yè)出版社，2003：212224． 附錄一:英文文獻(xiàn)原文Optimized Kinematics of Mechanical Presses with Noncircular GearsE. Doege ( l ) , M. HindersmannReceived on January 8, 1997Abstract：The quality of parts manufactured using metal forming operations depends to a large degree on the kinematics of the press ram. Noncircular gearsy to obtain those stroketime behaviours we aim at as an optimum for the various metal forming ope with a rotationalangledependent speed ratio in the press drive mechanism offer a new wa rations in terms of manufacturing. The paper explains the principle using a prototype press which was built by the Institute for Metal Forming and Metal Forming Machine Tools at Hanover University. It will present the kinematics as well as the forces and torques that occur in the prototype. Furthermore, the paper demonstrates using one example of deep drawing and one of forging that the press drive mechanism with noncircular gears may be used advantageously for virtually all metal forming operations.Keywords: Press, Gear, Kinematics1 lntroductiorIncreasing demands on quality in all areas of manufacturing engineering, in sheet metal forming as well as in forging, go hand in hand with the necessity to make production economical. Increasing market orientation requires that both technological and economic requirements be met. The improvement of quality, productivity and output by means of innovative solutions is one of the keys to maintaining and extending one39。 also to be considered is the time required for changing the part as well as for auxiliary operations in line with the priority of a short cycle time.2 Pressing Machine RequirementsOne manufacturing cycle, which corresponds to one stroke of the press goes through three stages: loading,forming and removing the part. Instead of the loading and removal stages we often find feeding the sheet, especially in sheer cutting. For this, the press ram must have a minimum height for a certain time. During the forming period the ram should have a particular velocity curve,which will be gone into below. The transitions between the periods should take place as quickly as possible to ensure short cycle time. The requirement of a short cycle time is for business reasons, to ensure low parts costs via high output. For this reason stroke numbers of about 24/min for the deep drawing of large automotive body sheets and 1200/min for automatic punching machines are standard the number of strokes in order to reduce cycle times without design changes to the pressing machine results in increasing strain rates, however. This has a clear effect on the forming process, which makes it necessary to consider the parameters which determine the process and are effected by it.In deep drawing operations, the velocity of impact when striking the sheet should be as low as possible to avoid the impact. On the one hand, velocity during forming must be sufficient for lubrication. On the other hand, we have to consider the rise in the yield stress corresponding to an increase in the strain rate which creates greater forces and which may cause fractures at the transition from the punch radius to the side wall of the part.In forging, short pressure dwell time is desirable. As the pressure dwell time drops the die surface temperature goes down and as a result the thermal wear This is counteracted by the enhanced mechanical wear due to the greater forming force, but the increase due to the strain rate is pensated by lower yield stress because of the lower cooling of the part. The optimal short pressure dwell can nowadays be determined quantitatively using the finite element method [3]. In addition to cost avoidance due to reduction in wear, short pressure dwell time is also an important technological requirement for the precision forging of near net shape parts, which has a promising future.The requirements of high part quality and high output will only be met by a machine technology which takes into account the demands of the metal forming process in equal measure to the goal of decreasing work production costs. Previous p