第一篇：機械設(shè)備管理規(guī)定中英文對照版

機械設(shè)備管理規(guī)定

Mechanical equipment regulations

1．總則

1.General rules

1.1為了加強項目部施工機械設(shè)備的管理，提高設(shè)備使用壽命和經(jīng)濟效益，保證設(shè)備安全生產(chǎn)和正常運行,特制訂本規(guī)定。

1.1 In order to strengthen the management of construction machinery and equipment of the project department , improve equipment life and economic efficiency, ensure safe production and normal operation of the equipment.1.2設(shè)備是項目部施工的物質(zhì)技術(shù)基礎(chǔ)，要貫徹執(zhí)行“預(yù)防為主”的方針，要堅持使用與保養(yǎng)相結(jié)合，修理與改造相結(jié)合，技術(shù)管理與經(jīng)濟效益相結(jié)合的原則。

1.2 Equipment is the material and technical basis of construction for the project department.Implement the “prevention first” principle and adhere to the principle of combining the use and maintenance, the repair and renovation, technology management and economic efficiency.1.3設(shè)備管理的主要任務(wù)是：貫徹落實上級有關(guān)方針、政策、法令、法規(guī)，通過技術(shù)和組織措施，做到全面規(guī)劃，合理配置，擇優(yōu)選購、正確使用，精心維護、科學檢修、適時改造和更新，既對設(shè)備進行綜合管理。保證設(shè)備完好，不斷改善和提高技術(shù)裝備素質(zhì)，充分發(fā)揮設(shè)備的綜合效能，為項目部提供性能優(yōu)良、安全可靠的設(shè)備，并使設(shè)備增值保值。

1.3 the main task of equipment management : to implement the relevant guidelines, policies, laws, regulations of the superior, through technical and organizational measures to achieve comprehensive planning, rational distribution, perfect purchase, the proper use, meticulously care, scientific maintenance, timely rehabilitation and renewal.That means the integrated management shall be applied for the equipment.Ensure that the equipment is intact, continually improve and enhance the quality of technical equipment and make full use of the integrated performance of the equipment, providing excellent, safe and reliable equipment for the project department while preserving and increasing the value of the equipment.1.4積極采用先進的設(shè)備管理方法和維修新技術(shù)，不斷提高設(shè)備管理和維修技術(shù)水平。

1.4 Actively apply advanced equipment management methods and new maintenance technology, and continually improve the management and maintenance technology standards for the equipment.1.5管好、用好、維修好、改造好設(shè)備，保證財產(chǎn)不受損失，使設(shè)備經(jīng)常保持良好的技術(shù)狀態(tài)，保證經(jīng)營發(fā)展和施工生產(chǎn)的需要，是項目部領(lǐng)導(dǎo)和各部門的重要職責。

1.5 The equipment shall be well managed, used, repaired, altered to ensure the property against loss.Keeping the equipment in good technical condition and ensuring to meet the needs of business development and construction are an important responsibility of the project leaders and various departments.2.設(shè)備的使用和保養(yǎng)規(guī)定

2.The use and maintenance regulations for the equipment

2.1設(shè)備的使用，大型設(shè)備必須人機固定，并實行機長負責制。鼓勵操作人員 1

（及其它工種）多學技術(shù)，成為一專多能的復(fù)合型人才，各設(shè)備之間操作人員以及當?shù)毓陀貌僮魅藛T調(diào)換頻繁，所以特規(guī)定對多班制、替班作業(yè)的設(shè)備，必須實行設(shè)備交接班制度，并認真填寫交接班記錄。

2.1 The person using the equipment, especially for large equipment, must be fixed and the captain responsibility system shall be implemented.Encourage operators(and other types of workers)to learn techniques and become complex talents who become expert in one field while possessing all-round.The operation staff between different types of equipment and locally employed operating staff exchange frequently, so the equipment shift system shall be implemented and the shift records shall be seriously recorded for the equipment which needs many shifts.2.2操作人員在獨立使用前，要對設(shè)備的性能、技術(shù)規(guī)范、維護知識和安全操作規(guī)程等技術(shù)理論教育以及實際操作技術(shù)培訓(xùn)，設(shè)備部會同安保部、辦公室對操作人員進行考試，經(jīng)過考試合格的，方可獨立操作（已在取得中國相應(yīng)工種技能等級證書的可免于技能考試）。雇傭當?shù)氐难拦げ僮魅藛T必須持證上崗。

2.2 Before the operator use the equipment independently, he shall be educated and trained on the performance of equipment, technical specifications, maintenance knowledge, safety procedures and other technical theories and practical skills.Equipment department in conjunction with HSE department and office shall arrange exams for the operating persons.After passing the examination, they shall operate the equipment independently(persons who have already achieved the relevant work skill level certificates are exempt from skill exams).The local operating workers hired from Jamaica must be employed with certificates.2.3大型設(shè)備使用前，設(shè)備使用部門/人員必須提前告知設(shè)備部設(shè)備使用計劃，以便合理安排預(yù)使用的設(shè)備。設(shè)備部應(yīng)做好鑰匙發(fā)放登記。設(shè)備操作人員須是經(jīng)過考試合格的人員。設(shè)備鑰匙交付后，設(shè)備由使用部門負責日常使用管理，原則上禁止牙籍操作人員將設(shè)備鑰匙帶回家，即每日上班時發(fā)放鑰匙，下班時收回鑰匙，設(shè)備使用專人專機。

2.3 Before using the large equipments, the equipment using department/ personnel shall inform the equipment department in advance about the equipment using plan so that they can pre-arrange for the equipments needed.The equipment department should make registration of the using situation of keys.The equipments operators should be qualified staff passing the examination.After the delivery of keys, the equipments should be maintained and managed daily by the using department.Regarding the principles, the local operators from Jamaica can not take the keys home.The reasonable principle is to distribute the keys at the time starting to work and take the keys back after they are off duty.The equipments should be operated by designated personnel.2.4設(shè)備操作人員對設(shè)備要實行日檢制度（每日進行例行保養(yǎng)檢查），并認真填寫記錄（施工機械工作日志），嚴格遵守《施工機械操作規(guī)程》和隨車《操作保養(yǎng)手冊》，做到精心操作，嚴禁超負荷、拼設(shè)備和帶病運轉(zhuǎn)。

2.4 The operators should check the equipments daily and fill in the records(construction machinery work diary)in real earnest.Strictly abide by the Construction machinery operating procedures and Operation & maintenance manuals.Operate carefully, do not overload and wrongly operate the

equipments.2.5操作人員必須熟練掌握“四懂”(懂性能、懂原理、懂結(jié)構(gòu)，懂用途)、“三會”（會操作、會保養(yǎng)、會排除故障）、“十字作業(yè)法”（調(diào)整、緊固、防腐、潤滑、清潔）。

2.5 The operator must be familiar with the “four understanding”(understand performance, understand the principles, understand the structure, understand function), “Three skills”(operation, maintenance, troubleshooting), and “Ten words operation method”(adjustment, tightening , corrosion prevention, lubrication, cleaning).2.6操作人員應(yīng)做到：“五不接”（機械狀況不良好不接、保養(yǎng)不良好不接、工具附件不齊全不接、原始記錄填寫不全不接，生產(chǎn)任務(wù)不清不接）;班前“兩件事”（檢查機械完好情況，進行例行保養(yǎng)、檢查電源或油料進行試車運轉(zhuǎn)）；班中“五注意”(注意訊號、聽從指揮，遵守規(guī)程、確保安全，重視質(zhì)量、配合生產(chǎn)，注意緊固、及時加油，傾聽聲音，觀察儀表)；班后“五不走”（電源不切斷不走、機械設(shè)備清洗保養(yǎng)不徹底不走、工具附件丟失找不到不走、不辦清接班手續(xù)不走、不做好原始記錄不走）；對設(shè)備潤滑做到“五定”（定人、定質(zhì)、定量、定點、定時），切實做好潤滑工作。

2.6 The operator should follow: “Five unacceptable circumstances ”(no accept when the mechanical condition is poor, no accept when the maintenance is bad , no accept when tools and accessories are not complete, no accept when the original record is not complete, no accept when the production tasks are not clear);the “two thing ” before work(check conditions of machinery, conduct routine maintenance, power or fuel check and perform trial operation);“ five note ” during work(note the signal, obey the command, comply with regulations, ensure the safety, pay attention to quality, assist with production, pay attention to fastening, refuel timely , listen to the sound, observe instruments);“no departure under five circumstances”(do not leave without cutting off the power does , do not leave without conduct thoroughly cleaning and maintenance for machinery and equipment, do not leave without finding the lost tools and accessories, do not leave without finishing succession procedures, do not leave without making original records);“five points to be fixed” for equipment lubrication(fixed people, fixed quality, fixed quantity, fixed place, fixed time), achieving really good lubrication.3.設(shè)備的修理

3.Repair of the equipment

3.1設(shè)備日常維修保養(yǎng)工作由維修班組織實施，并做好維修保養(yǎng)記錄。

3.1 The maintenance team shall organize and implement routine repair and maintenance work for the equipment and make maintenance records.3.2設(shè)備修理按照“養(yǎng)修并重、預(yù)防為主”的原則，實行計劃養(yǎng)護、狀態(tài)檢測與故障診斷修理。

3.2 For the equipment repair, be in accordance with the principle of “both maintenance and repair, prevention-oriented” and implement the repair through planned maintenance, state detection and fault diagnosis.3.3設(shè)備部根據(jù)設(shè)備運轉(zhuǎn)小時數(shù)、使用人員填寫的機械設(shè)備工作日志、設(shè)備月檢記錄結(jié)合實際情況，根據(jù)設(shè)備的動力性、經(jīng)濟性、安全性，制訂修理計劃。并加強修理工藝的管理，確保修理質(zhì)量，縮短停修時間；修理時應(yīng)根據(jù)具體條件制

訂合理的修理工藝、技術(shù)標準，從目前的綜合性修理逐步過渡到按部件分工修理，并積極創(chuàng)造條件逐步實行總稱互換修理。

The equipment department shall develop the repair plan according to the equipment operating hours, machinery and equipment work log written by using staff, equipment monthly inspection record and the actual situation.The power, economy efficiency and safety shall be taken into consideration.The equipment department shall strengthen the management of repair technology to ensure the repair quality and to short repair time.A reasonable repairing technology and technical standards shall be formulated for the repair according to the actual conditions.The current comprehensive repair shall be gradually transited to the repair based on different parts, actively creating conditions for achieve interchangeable repair.3.4設(shè)備大修過程中，設(shè)備部要嚴格把關(guān)，首先確定機務(wù)主辦，并填寫技術(shù)交底和安全/環(huán)保技術(shù)交底，修理人員必須認真做好修理過程中的多項基礎(chǔ)工作。

3.4 during the thorough repair for the equipment , equipment department shall strictly control procedures.First, determine the machinery supervisor and complete technical disclosure and safety / environmental technical disclosure.The repairman must earnestly do various basic works during repair process.3.4.1嚴把修理關(guān)，嚴格執(zhí)行修理前、修理中和修理后的三檢制度。修理前，要做好拆檢記錄，拆檢項目，零部件損壞情況，運動件的磨損情況及測量的數(shù)據(jù)等。

3.4.1 strictly control procedures of repair and implement the inspection system pre-repair, under repair and after repair.Before repair, make records on dismantling , such as dismantling items, damaged conditions of spare parts, wear of moving parts, measuring data and so on.3.4.2嚴把配件關(guān)，對于質(zhì)量不合格的材料配件不準使用，質(zhì)量不合格的總成不準裝配，所用的材料配件和修理質(zhì)量均按規(guī)定標準進行檢驗。

3.4.2 strictly manage the accessories.Materials and accessories which are of substandard quality materials are not allowed to use.The assemblies which are of substandard quality are not allowed to be assembled.Conduct inspection for materials, accessories and repair quality according to the provisions of the standards.3.4.3修理過程中，盡量做到修舊利廢，要認真推廣：“焊、補、噴、鍍、鉚、鑲、配、改、校、漲、縮、粘”十二字修舊經(jīng)驗，不斷擴大修舊范圍，保證修舊質(zhì)量，節(jié)約修理資金，降低修理成本。

3.4.3 during repair process, the old equipment shall be repaired and the waste shall be fully used, earnestly implement the “ twelve words guideline”, that is welding, mend, spray, plating, riveting, mount, match, change, check , expand, shrink, stick.The repair range shall be expand, the repair quality shall be ensured, the repair money shall be saved, and the repair cost shall be reduced.3.4.4設(shè)備修理完畢，機務(wù)科要組織竣工驗收，進行試運轉(zhuǎn)，并做好記錄，填寫竣工驗收資料。廢零件、廢油、廢料（油手套、油棉紗）要回收，并交有關(guān)部門處置，做到工完、料凈、場地清。

3.4.4 when the repair for the equipment is completed, mechanical department shall organize the completion acceptance, conduct test run, make a record and fill in the completion acceptance data.Scrap parts, waste oil and

waste material(oil gloves and oil cotton yarn)shall be recycled and transferred to relevant departments for disposal, so when the work is finished, the material is fully used and the site is clean.3.4.5設(shè)備大修出廠應(yīng)嚴格按技術(shù)要求進行大修走合期。

3.4.5The breaking-in period shall be strictly arranged according to the technical requirements for the equipment which has gone through a thorough repair in the factory.3.5設(shè)備的技術(shù)革新與技術(shù)改造可根據(jù)生產(chǎn)需要和設(shè)備技術(shù)狀況，結(jié)合大修進行，積極推廣和應(yīng)用新技術(shù)、新工藝、新材料。

3.5 Technological innovation and transformation for the equipment shall be conducted according to the production needs and equipment technical conditions, combining with the thorough repair.The new technologies, new processes and new materials shall be actively promoted and applied.4.設(shè)備安全管理

4.Safety management of equipment

4.1設(shè)備安全工作必須落實“安全第一，預(yù)防為主”的方針，嚴格執(zhí)行公司及當?shù)卣嘘P(guān)安全生產(chǎn)的規(guī)定。

4.1 Equipment safety work shall be done in accordance with the “safety first, prevention first” principle.strictly implement the provisions of the company and the local government on production safety.4.2 項目部根據(jù)施工特點，建立健全設(shè)備安全制度和安全組織，認真貫徹執(zhí)行各類設(shè)備的安全操作規(guī)程和保養(yǎng)檢修規(guī)程，使設(shè)備安全管理工作落到實處。

4.2 The project department shall establish and improve the safety systems and safety organizations for the equipment according to the construction characteristics, and earnestly implement safe operation procedures and maintenance and service procedures of various types of equipment, making the equipment safety management fall into place.4.3各類機械設(shè)備都應(yīng)有可靠的安全裝置和防護措施，保證設(shè)備的安全運行。

4.3 All types of machinery and equipment should have reliable safety devices and protective measures to ensure the safe operation of the equipment.4.4設(shè)備操作人員必須熟知機械基本原理與構(gòu)造，熟悉安全操作規(guī)程，掌握有關(guān)安全生產(chǎn)的知識和值班運轉(zhuǎn)制度，設(shè)備運轉(zhuǎn)時發(fā)現(xiàn)異常，要立即采取措施。

4.4 Equipment operators must be familiar with the basic mechanical principles and structure, the safety procedures, knowledge on production safety and duty operating system.If the equipment operation is abnormal, take measures immediately.4.5項目部根據(jù)實際情況與設(shè)備操作人員簽訂“設(shè)備操作責任書”，界定責任范圍。

4.5 Project Department shall sign a “equipment operating responsibility agreement” with equipment operators according to the actual situation to define the responsibility scope.4.6項目部制訂設(shè)備安全事故的防范措施及事故應(yīng)急預(yù)案，經(jīng)常組織學習，加強設(shè)備安全教育。

4.6 Project Department shall develop equipment security accident

prevention measures and emergency plans, frequently organize learning, and enhance equipment safety education.

第二篇：機械名稱中英文對照

一、除大塊機Eliminates the bulk machine

二、齒型篩分除雜物機The screening and eliminates the sundry goods machine

三、振動煤箅Vibration Coal Grate

四、滾軸篩Roller Screen

五、滾筒篩Trommel Screen

六、振動概率篩Vibration Probability Screen

七、減振平臺Antivibration Platform

八、布料器Distributing Device

九、皮帶機頭部伸縮裝置Conveyer Belt Telescopiform Device

十、膠帶給料機Belt Feeder

十一、往復(fù)式給料機Reciprocating Feeder

十二、振動給煤機Vibrator Feeder

十三、葉輪給煤機Coal Impeller Feeder

十四、埋刮板輸送機Buried Scraper Conveyer

十五、螺旋輸送機Screw Conveyer

十六、板式喂料機Apron Feeder

十七、緩沖彈簧板式大塊輸送機Buffer Spring Apron Bulk Converyor

十八、斗式提升機Chain-Bucket Elevator

十九、TD75、DTⅡ型帶式輸送機Type TD75/DTII Belt Conveyer

二十、電動三通3-Through-Chute With Electric Drive Gate 二

十一、重力式煤溝擋板Gravity Type Coal Ditch Baffle

二十二、物料穩(wěn)流器Material Constant Staticizer

二十三、犁式卸料器、刮水器Plough Type Tripper/Wiper 二

十四、棧橋沖洗器Flusher

二十五、噴霧除塵系統(tǒng)Exhaust System 二

十六、緩沖鎖氣器Buffer Air Lock 二

十七、緩沖滾筒Snub Pulley二十八、二十九、三

十、緩沖平臺Buffer Platform 膠帶防撕裂保護裝置Belt Protective Device 鏈斗卸車機Bucket-Chain Unloader

第三篇：機械專業(yè)論文中英文對照

Gearbox Noise?Correlation with Transmission Error and Influence of Bearing Preload

ABSTRACT The five appended papers all deal with gearbox noise and vibration.The first paper presents a review of previously published literature on gearbox noise and vibration.The second paper describes a test rig that was specially designed and built for noise testing of gears.Finite element analysis was used to predict the dynamic properties of the test rig, and experimental modal analysis of the gearbox housing was used to verify the theoretical predictions of natural frequencies.In the third paper, the influence of gear finishing method and gear deviations on gearbox noise is investigated in what is primarily an experimental study.Eleven test gear pairs were manufactured using three different finishing methods.Transmission error, which is considered to be an important excitation mechanism for gear noise, was measured as well as predicted.The test rig was used to measure gearbox noise and vibration for the different test gear pairs.The measured noise and vibration levels were compared with the predicted and measured transmission error.Most of the experimental results can be interpreted in terms of measured and predicted transmission error.However, it does not seem possible to identify one single parameter,such as measured peak-to-peak transmission error, that can be directly related to measured noise and vibration.The measurements also show that disassembly and reassembly of the gearbox with the same gear pair can change the levels of measured noise and vibration considerably.This finding indicates that other factors besides the gears affect gear noise.In the fourth paper, the influence of bearing endplay or preload on gearbox noise and vibration is investigated.Vibration measurements were carried out at torque levels of 140 Nm and 400Nm, with 0.15 mm and 0 mm bearing endplay, and with 0.15 mm bearing preload.The results show that the bearing endplay and preload

influence the gearbox vibrations.With preloaded bearings, the vibrations increase at speeds over 2000 rpm and decrease at speeds below 2000 rpm, compared with bearings with endplay.Finite element simulations show the same tendencies as the measurements.The fifth paper describes how gearbox noise is reduced by optimizing the gear geometry for decreased transmission error.Robustness with respect to gear deviations and varying torque is considered in order to find a gear geometry giving low noise in an appropriate torque range despite deviations from the nominal geometry due to manufacturing tolerances.Static and dynamic transmission error, noise, and housing vibrations were measured.The correlation between dynamic transmission error, housing vibrations and noise was investigated in speed sweeps from 500 to 2500 rpm at constant torque.No correlation was found between dynamic transmission error and noise.Static loaded transmission error seems to be correlated with the ability of the gear pair to excite vibration in the gearbox dynamic system.Keywords: gear, gearbox, noise, vibration, transmission error, bearing preload.ACKNOWLEDGEMENTS This work was carried out at Volvo Construction Equipment in Eskilstuna and at the Department of Machine Design at the Royal Institute of Technology(KTH)in Stockholm.The work was initiated by Professor Jack Samuelsson(Volvo and KTH), Professor S?ren Andersson(KTH), and Dr.Lars Br?the(Volvo).The financial support of the Swedish Foundation for Strategic Research and the Swedish Agency for Innovation Systems – VINNOVA – is gratefully acknowledged.Volvo Construction Equipment is acknowledged for giving me the opportunity to devote time to this work.Professor S?ren Andersson is gratefully acknowledged for excellent guidance and encouragement.I also wish to express my appreciation to my colleagues at the Department of Machine Design, and especially to Dr.Ulf Sellgren for performing simulations and contributing to the writing of Paper D, and Dr.Stefan Bj?rklund for performing surface finish measurements.The contributions to Paper C by Dr.Mikael

P?rssinen are highly appreciated.All contributionsto this work by colleagues at Volvo are gratefully appreciated.1 INTRODUCTION 1.1 Background Noise is increasingly considered an environmental issue.This belief is reflected in demands for lower noise levels in many areas of society, including the working environment.Employees spend a lot of time in this environment and noise can lead not only to hearing impairment but also to decreased ability to concentrate, resulting in decreased productivity and an increased risk of accidents.Quality, too, has become increasingly important.The quality of a product can be defined as its ability to fulfill customers’ demands.These demands often change over time, and the best competitors in the market will set the standard.Noise concerns are also expressed in relation to construction machinery such as wheel loaders and articulated haulers.The gearbox is sometimes the dominant source of noise in these machines.Even if the gear noise is not the loudest source, its pure high frequency tone is easily distinguished from other noise sources and is often perceived as unpleasant.The noise creates an impression of poor quality.In order not to be heard, gear noise must be at least 15 dB lower than other noise sources, such as engine noise.1.2 Gear noise This dissertation deals with the kind of gearbox noise that is generated by gears under load.This noise is often referred to as “gear whine” and consists mainly of pure tones at high frequencies corresponding to the gear mesh frequency and multiples thereof, which are known as harmonics.A tone with the same frequency as the gear mesh frequency is designated the gear mesh harmonic, a tone with a frequency twice the gear mesh frequency is designated the second harmonic, and so on.The term “gear mesh harmonics” refers to all multiples of the gear mesh frequency.Transmission error(TE)is considered an important excitation mechanism for gear whine.Welbourn [1] defines transmission error as “the difference between

the actual position of the output gear and the position it would occupy if the gear drive were perfectly conjugate.” Transmission error may be expressed as angular displacement or as linear displacement at the pitch point.Transmission error is caused by deflections, geometric errors, and geometric modifications.In addition to gear whine, other possible noise-generating mechanisms in gearboxes include gear rattle from gears running against each other without load, and noise generated by bearings.In the case of automatic gearboxes, noise can also be generated by internal oil pumps and by clutches.None of these mechanisms are dealt with in this work, and from now on “gear noise” or “gearbox noise” refers to “gear whine”.MackAldener [2] describes the noise generation process from a gearbox as consisting of three parts: excitation, transmission, and radiation.The origin of the noise is the gear mesh, in which vibrations are created(excitation), mainly due to transmission error.The vibrations are transmitted via the gears, shafts, and bearings to the housing(transmission).The housing vibrates, creating pressure variations in the surrounding air that are perceived as noise(radiation).Gear noise can be affected by changing any one of these three mechanisms.This dissertation deals mainly with excitation, but transmission is also discussed in the section of the literature survey concerning dynamic models, and in the modal analysis of the test gearbox in Paper B.Transmission of vibrations is also investigated in Paper D, which deals with the influence of bearing endplay or preload on gearbox noise.Differences in bearing preload influence a bearing’s dynamic properties like stiffness and damping.These properties also affect the vibration of the gearbox housing.1.3 Objective The objective of this dissertation is to contribute to knowledge about gearbox noise.The following specific areas will be the focus of this study: 1.The influence of gear finishing method and gear modifications and errors on noise and vibration from a gearbox.2.The correlation between gear deviations, predicted transmission error, measured transmission error, and gearbox noise.3.The influence of bearing preload on gearbox noise.4.Optimization of gear geometry for low transmission error, taking into consideration robustness with respect to torque and manufacturing tolerances.2 AN INDUSTRIAL APPLICATION ? TRANSMISSION NOISE REDUCTION 2.1 Introduction This section briefly describes the activities involved in reducing gear noise from a wheel loader transmission.The aim is to show how the optimization of the gear geometry described in Paper E is used in an industrial application.The author was project manager for the “noise work team” and performed the gear optimization.One of the requirements when developing a new automatic power transmission for a wheel loader was improving the transmission gear noise.The existing power transmission was known to be noisy.When driving at high speed in fourth gear, a high frequency gear-whine could be heard.Thus there were now demands for improved sound quality.The transmission is a typical wheel loader power transmission, consisting of a torque converter, a gearbox with four forward speeds and four reverse speeds, and a dropbox partly integrated with the gearbox.The dropbox is a chain of four gears transferring the powerto the output shaft.The gears are engaged by wet multi-disc clutches actuated by the transmission hydraulic and control system.2.2 Gear noise target for the new transmission Experience has shown that the high frequency gear noise should be at least 15 dB below other noise sources such as the engine in order not to be perceived as disturbing or unpleasant.Measurements showed that if the gear noise could be decreased by 10 dB, this criterion should be satisfied with some margin.Frequency analysis of the noise measured in the driver's cab showed that the dominant noise from the transmission originated from the dropbox gears.The goal for transmission noise was thus formulated as follows: “The gear noise(sound pressure level)from the dropbox

gears in the transmission should be decreased by 10 dB compared to the existing transmission in order not to be perceived as unpleasant.It was assumed that it would be necessary to make changes to both the gears and the transmission housing in order to decrease the gear noise sound pressure level by 10 dB.2.3 Noise and vibration measurements In order to establish a reference for the new transmission, noise and vibration were measured for the existing transmission.The transmission is driven by the same type of diesel engine used in a wheel loader.The engine and transmission are attached to the stand using the same rubber mounts that are used in a wheel loader in order to make the installation as similar as possible to the installation in a wheel loader.The output shaft is braked using an electrical brake.2.4 Optimization of gears Noise-optimized dropbox gears were designed by choosing macro-and microgeometries giving lower transmission error than the original(reference)gears.The gear geometry was chosen to yield a low transmission error for the relevant torque range, while also taking into consideration variations in the microgeometry due to manufacturing tolerances.The optimization of one gear pair is described in more detail in Paper E.Transmission error is considered an important excitation mechanism for gear whine.Welbourn [1] defines it as “the difference between the actual position of the output gear and the position it would occupy if the gear drive were perfectly conjugate.” In this project the aim was to reduce the maximum predicted transmission error amplitude at gear mesh frequency(first harmonic of gear mesh frequency)to less than 50% of the value for the reference gear pair.The first harmonic of transmission error is the amplitude of the part of the total transmission error that varies with a frequency equal to the gear mesh frequency.A torque range of 100 to 500 Nm was chosen because this is the torque interval in which the gear pair generates noise in its design application.According to Welbourn [1], a 50% reduction in transmission error can be expected to reduce gearbox noise by 6 dB

(sound pressure level, SPL).Transmission error was calculated using the LDP software(Load Distribution Program)developed at the Gear Laboratory at Ohio State University [3].The “optimization” was not strictly mathematical.The design was optimized by calculating the transmission error for different geometries, and then choosing a geometry that seemed to be a good compromise, considering not only the transmission error, but also factors such asstrength, losses, weight, cost, axial forces on bearings, and manufacturing.When choosing microgeometric modifications and tolerances, it is important to take manufacturing options and cost into consideration.The goal was to use the same finishing method for the optimized gears as for the reference gears, namely grinding using a KAPP VAS 531 and CBN-coated grinding wheels.For a specific torque and gear macrogeometry, it is possible to define a gear microgeometry that minimizes transmission error.For example, at no load, if there are no pitch errors and no other geometrical deviations, the shape of the gear teeth should be true involute, without modifications like tip relief or involute crowning.For a specific torque, the geometry of the gear should be designed in such a way that it compensates for the differences in deflection related to stiffness variations in the gear mesh.However, even if it is possible to define the optimal gear microgeometry, it may not be possible to manufacture it, given the limitations of gear machining.Consideration must also be given to how to specify the gear geometry in drawings and how to measure the gear in an inspection machine.In many applications there is also a torque range over which the transmission error should be minimized.Given that manufacturing tolerances are inevitable, and that a demand for smaller tolerances leads to higher manufacturing costs, it is important that gears be robust.In other words, the important characteristics, in this case transmission error, must not vary much when the torque is varied or when the microgeometry of the gear teeth varies due to manufacturing tolerances.LDP [3] was used to calculate the transmission error for the reference and optimized gear pair at different torque levels.The robustness function in LDP was used to analyze the sensitivity to deviations due to manufacturing tolerances.The “min, max, level” method involves assigning three levels to each parameter.2.5 Optimization of transmission housing Finite element analysis was used to optimize the transmission housing.The optimization was not performed in a strictly mathematical way, but was done by calculating the vibration of the housing for different geometries and then choosing a geometry that seemed to be a good compromise.Vibration was not the sole consideration, also weight, cost, available space, and casting were considered.A simplified shell element model was used for the optimization to decrease computational time.This model was checked against a more detailed solid element model of the housing to ensure that the simplification had not changed the dynamic properties too much.Experimental modal analysis was also used to find the natural frequencies of the real transmission housing and to ensure that the model did not deviate too much from the real housing.Gears shafts and bearings were modeled as point masses and beams.The model was excited at the bearing positions by applying forces in the frequency range from 1000 to 3000 Hz.The force amplitude was chosen as 10% of the static load from the gears.This choice could be justified because only relative differences are of interest, not absolute values.The finite element analysis was performed by Torbj?rn Johansen at Volvo Technology.The author’s contribution was the evaluation of the results of different housing geometries.A number of measuring points were chosen in areas with high vibration velocities.At each measuring point the vibration response due to the excitation was evaluated as a power spectral density(PSD)graph.The goal of the housing redesign was to decrease the vibrations at all measuring points in the frequency range 1000 to 3000 Hz.2.6 Results of the noise measurements The noise and vibration measurements described in section 2.3 were performed after optimizing the gears and transmission housing.The total sound power level decreased by 4 dB.2.7 Discussion and conclusions It seems to be possible to decrease the gear noise from a transmission by

decreasing the static loaded transmission error and/or optimizing the housing.In the present study, it is impossible to say how much of the decrease is due to the gear optimization and how much to the housing optimization.Answering this question would have required at least one more noise measurement, but time and cost issues precluded this.It would also have been interesting to perform the noise measurements on a number of transmissions, both before and after optimizing the gears and housing, in order to determine the scatter of the noise of the transmissions.Even though the goal of decreasing the gear noise by 10 dB was not reached, the goal of reducing the gear noise in the wheel loader cab to 15 dB below the overall noise was achieved.Thus the noise optimization was successful.3 SUMMARY OF APPENDED PAPERS 3.1 Paper A: Gear Noise and Vibration – A Literature Survey This paper presents an overview of the literature on gear noise and vibration.It is divided into three sections dealing with transmission error, dynamic models, and noise and vibration measurement.Transmission error is an important excitation mechanism for gear noise and vibration.It is defined as “the difference between the actual position of the output gear and the position it would occupy if the gear drive were perfectly conjugate” [1].The literature survey revealed that while most authors agree that transmission error is an important excitation mechanism for gear noise and vibration, it is not the only one.Other possible time-varying noise excitation mechanisms include friction and bending moment.Noise produced by these mechanisms may be of the same order of magnitude as that produced by transmission error, at least in the case of gears with low transmission error [4].The second section of the paper deals with dynamic modeling of gearboxes.Dynamic models are often used to predict gear-induced vibrations and investigate the effect of changes to the gears, shafts, bearings, and housing.The literature survey revealed that dynamic models of a system consisting of gears, shafts, bearings, and gearbox casing can be useful in understanding and predicting the dynamic behavior of a gearbox.For

relatively simple gear systems, lumped parameter dynamic models with springs, masses, and viscous damping can be used.For more complex models that include such elements as the gearbox housing, finite element modeling is often used.The third section of the paper deals with noise and vibration measurement and signal analysis, which are used when experimentally investigating gear noise.The survey shows that these are useful tools in experimental investigation of gear noise because gears create noise at specific frequencies related to the number of teeth and the rotational speed of the gear.3.2 Paper B: Gear Test Rig for Noise and Vibration Testing of Cylindrical Gears Paper B describes a test rig for noise testing of gears.The rig is of the recirculating power type and consists of two identical gearboxes, connected to each other with two universal joint shafts.Torque is applied by tilting one of the gearboxes around one of its axles.This tilting is made possible by bearings between the gearbox and the supporting brackets.A hydraulic cylinder creates the tilting force.Finite element analysis was used to predict the natural frequencies and mode shapes for individual components and for the complete gearbox.Experimental modal analysis was carried out on the gearbox housing, and the results showed that the FE predictions agree with the measured frequencies(error less than 10%).The FE model of the complete gearbox was also used in a harmonic response analysis.A sinusoidal force was applied in the gear mesh and the corresponding vibration amplitude at a point on the gearbox housing was predicted.3.3 Paper C: A Study of Gear Noise and Vibration Paper C reports on an experimental investigation of the influence of gear finishing methods and gear deviations on gearbox noise and vibration.Test gears were manufactured using three different finishing methods and with different gear tooth modifications and deviations.Table3.3.1 gives an overview of the test gear pairs.The surface finishes and geometries of the gear tooth flanks were measured.Transmission error was measured using a single flank gear tester.LDP software from Ohio State University was used for transmission error computations.The test rig described in Paper B was used to measure gearbox noise and vibration for the different test gear pairs.The measurements showed that disassembly and reassembly of the gearbox with the same gear pair might change the levels of measured noise and vibration.The rebuild variation was sometimes of the same order of magnitude as the differences between different tested gear pairs, indicating that other factors besides the gears affect gear noise.In a study of the influence of gear design on noise, Oswald et al.[5] reported rebuild variations of the same order of magnitude.Different gear finishing methods produce different surface finishes and structures, as well as different geometries and deviations of the gear tooth flanks, all of which influence the transmission error and thus the noise level from a gearbox.Most of the experimental results can be explained in terms of measured and computed transmission error.The relationship between predicted peak-to-peak transmission error and measured noise at a torque level of 500 Nm is shown in Figure 3.3.1.There appears to be a strong correlation between computed transmission error and noise for all cases except gear pair K.However, this correlation breaks down in Figure 3.3.2, which shows the relationship between predicted peak to peak transmission error and measured noise at a torque level of 140 Nm.The final conclusion is that it may not be possible to identify a single parameter, such as peak-to-peak transmission error, that can be directly related to measured noise and vibration.3.4 Paper D: Gearbox Noise and Vibration ?Influence of Bearing Preload The influence of bearing endplay or preload on gearbox noise and vibrations is investigated in Paper D.Measurements were carried out on a test gearbox consisting of a helical gear pair, shafts, tapered roller bearings, and a housing.Vibration measurements were carried out at torque levels of 140 Nm and 400 Nm with 0.15 mm and 0 mm bearing endplay and with 0.15 mm bearing preload.The results shows that the bearing endplay or preload influence gearbox vibrations.Compared with bearings

with endplay, preloaded bearings show an increase in vibrations at speeds over 2000 rpm and a decrease at speeds below 2000 rpm.Figure 3.4.1 is a typical result showing the influence of bearing preload on gearbox housing vibration.After the first measurement, the gearbox was not disassembled or removed from the test rig.Only the bearing preload/endplay was changed from 0 mm endplay/preload to 0.15 mm preload.Therefore the differences between the two measurements are solely due to different bearing preload.FE simulations performed by Sellgren and ?kerblom [6] show the same trend as the measurements here.For the test gearbox, it seems that bearing preload, compared with endplay, decreased the vibrations at speeds below 2000 rpm and increased vibrations at speeds over 2000 rpm, at least at a torque level of 140 Nm.3.5 Paper E: Gear Geometry for Reduced and Robust Transmission Error and Gearbox Noise In Paper E, gearbox noise is reduced by optimization of gear geometry for decreased transmission error.The optimization was not performed strictly mathematically.It was done by calculating the transmission error for different geometries and then choosing a geometry that seemed to be a good compromise considering not only the transmission error, but also other important characteristics.Robustness with respect to gear deviations and varying torque was considered in order to find gear geometry with low transmission error in the appropriate torque range despite deviations from the nominal geometry due to manufacturing tolerances.Static and dynamic transmission error as well as noise and housing vibrations were measured.The correlation between dynamic transmission error, housing vibrations, and noise was investigated in a speed sweep from 500 to 2500 rpm at constant torque.No correlation was found between dynamic transmission error and noise.4 DISCUSSION AND CONCLUSIONS Static loaded transmission error seems to be strongly correlated to gearbox noise.Dynamic transmission error does not seem to be correlated to gearbox noise in speed

sweeps in these investigations.Henriksson [7] found a correlation between dynamic transmission error and gearbox noise when testing a truck gearbox at constant speed and different torque levels.The different test conditions, speed sweep versus constant speed, and the different complexity(a simple test gearbox versus a complete truck gearbox)may explain the different results regarding correlation between dynamic transmission error and gearbox noise.Bearing preload influences gearbox noise, but it is not possible to make any general statement as to whether preload is better than endplay.The answer depends on the frequency and other components in the complex dynamic system of gears, shafts, bearings, and housing.To minimize noise, the gearbox housing should be as rigid as possible.This was proposed by Rook [8], and his views are supported by the results relating to the optimization of a transmission housing described in section 2.5.Finite element analysis is a useful tool for optimizing gearbox housings.5 FUTURE RESEARCH It would be interesting to investigate the correlation between dynamic transmission error and gearbox noise for a complete wheel loader transmission.One challenge would be to measure transmission error as close as possible to the gears and to avoid resonances in the connection between gear and encoder.The dropbox gears in a typical wheel loader transmission are probably the gears that are most easily accessible for measurement using optical encoders.See Figure 5.1.1 for possible encoder positions.Modeling the transmission in more detail could be another challenge for future work.One approach could be to use a model of gears, shafts, and bearings using the transmission error as the excitation.This could be a finite element model or a multibody system model.The output from this model would be the forces at the bearing positions.The forces could be used to excite a finite element model of the housing.The housing model could be used to predict noise radiation, and/or vibration at the attachment points for the gearbox.This approach would give absolute values, not just relative levels.REFERENCES [1] Welbourn D.B., “Fundamental Knowledge of Gear Noise ??A Survey”, Proc.Noise & Vib.of Eng.and Trans., I Mech E., Cranfield, UK, July 1979, pp 9–14.[2] MackAldener M., “Tooth Interior Fatigue Fracture & Robustness of Gears”, Royal Institute of Technology, Doctoral Thesis, ISSN 1400-1179, Stockholm, 2001.[3] Ohio State University, LDP Load Distribution Program, Version 2.2.0, http://004km.cn/ , 2007.[4] Borner J., and Houser D.R., “Friction and Bending Moments as Gear Noise Excitations”,SAE Technical Paper 961816.[5] Oswald F.B.et al., “Influence of Gear Design on Gearbox Radiated Noise”, Gear Technology, pp 10–15, 1998.[6] Sellgren U., and ?kerblom M., “A Model-Based Design Study of Gearbox Induced Noise”, International Design Conference – Design 2004, May 18-21, Dubrovnik, 2004.[7] Henriksson M., “Analysis of Dynamic Transmission Error and Noise from a Two-stage Gearbox”, Licentiate Thesis, TRITA-AVE-2005:34 / ISSN-1651-7660, Stockholm, 2005.[8] Rook T., “Vibratory Power Flow Through Joints and Bearings with Application to Structural Elements and Gearboxes”, Doctoral Thesis, Ohio State University, 1995.

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英語原文

NUMERICAL CONTROL

Numerical control(N/C)is a form of programmable automation in which the processing equipment is controlled by means of numbers, letters, and other symbols, The numbers, letters, and symbols are coded in an appropriate format to define a program of instructions for a particular work part or job.When the job changes, the program of instructions is changed.The capability to change the program is what makes N/C suitable for low-and medium-volume production.It is much easier to write programs than to make major alterations of the processing equipment.There are two basic types of numerically controlled machine tools：point—to—point and continuous—path(also called contouring).Point—to—point machines use unsynchronized motors, with the result that the position of the machining head Can be assured only upon completion of a movement, or while only one motor is running.Machines of this type are principally used for straight—line cuts or for drilling or boring.The N/C system consists of the following components：data input, the tape reader with the control unit, feedback devices, and the metal—cutting machine tool or other type of N/C equipment.Data input, also called “man—to—control link”, may be provided to the machine tool manually, or entirely by automatic means.Manual methods when used as the sole source of input data are restricted to a relatively small number of inputs.Examples of manually operated devices are keyboard dials, pushbuttons, switches, or thumbwheel selectors.These are located on a console near the machine.Dials ale analog devices usually connected to a syn-chro-type resolver or potentiometer.In most cases, pushbuttons, switches, and other similar types of selectors are digital input devices.Manual input requires that the operator set the controls for each operation.It is a slow and tedious process and is seldom justified except in elementary machining applications or in special cases.In practically all cases, information is automatically supplied to the control unit and the machine tool by cards, punched tapes, or by magnetic tape.Eight—channel punched paper tape is the most commonly used form of data input for conventional N/C systems.The coded instructions on the tape consist of sections of punched holes called blocks.Each block represents a machine function, a machining operation, or a combination of the two.The entire N/C program on a tape is made up of an accumulation of these successive data blocks.Programs resulting in long tapes all wound on reels like motion-picture film.Programs on relatively short tapes may be continuously repeated by joining the two ends of the tape to form a loop.Once installed, the tape is used again and again without further handling.In this case, the operator simply loads and1

unloads the parts.Punched tapes ale prepared on type writers with special tape—punching attachments or in tape punching units connected directly to a computer system.Tape production is rarely error-free.Errors may be initially caused by the part programmer, in card punching or compilation, or as a result of physical damage to the tape during handling, etc.Several trial runs are often necessary to remove all errors and produce an acceptable working tape.While the data on the tape is fed automatically, the actual programming steps ale done manually.Before the coded tape may be prepared, the programmer, often working with a planner or a process engineer, must select the appropriate N/C machine tool, determine the kind of material to be machined, calculate the speeds and feeds, and decide upon the type of tooling needed.The dimensions on the part print are closely examined to determine a suitable zero reference point from which to start the program.A program manuscript is then written which gives coded numerical instructions describing the sequence of operations that the machine tool is required to follow to cut the part to the drawing specifications.The control unit receives and stores all coded data until a complete block of information has been accumulated.It then interprets the coded instruction and directs the machine tool through the required motions.The function of the control unit may be better understood by comparing it to the action of a dial telephone, where, as each digit is dialed, it is stored.When the entire number has been dialed, the equipment becomes activated and the call is completed.Silicon photo diodes, located in the tape reader head on the control unit, detect light as it passes through the holes in the moving tape.The light beams are converted to electrical energy, which is amplified to further strengthen the signal.The signals are then sent to registers in the control unit, where actuation signals are relayed to the machine tool drives.Some photoelectric devices are capable of reading at rates up to 1000 characters per second.High reading rates are necessary to maintain continuous machine—tool motion；otherwise dwell marks may be generated by the cutter on the part during contouring operations.The reading device must be capable of reading data blocks at a rate faster than the control system can process the data.A feedback device is a safeguard used on some N/C installations to constantly compensate for errors between the commanded position and the actual location of the moving slides of the machine tool.An N/C machine equipped with this kind of a direct feedback checking device has what is known as a closed-loop system.Positioning control is accomplished by a sensor which, during the actual operation, records the position of the slides and relays this information back to the control unit.Signals thus received ale compared to input signals on the tape, and any discrepancy between them is automatically rectified.In an alternative system, called an open—loop system, the machine is positioned solely by stepping motor drives in response to commands by a controllers.There is one basic type of NC motions.Point-to-point or Positional Control In point-to-point control the machine tool elements(tools, table, etc.)are moved to programmed locations and the machining operations performed

after the motions are completed.The path or speed of movement between locations is unimportant;only the coordinates of the end points of the motions are accurately controlled.This type of control is suitable for drill presses and some boring machines, where drilling, tapping, or boring operations must be performed at various locations on the work piece.Straight-Line or Linear Control Straight-Line control systems are able to move the cutting tool parallel to one of the major axes of the machine tool at a controlled rate suitable for machining.It is normally only possible to move in one direction at a time, so angular cuts on the work piece are not possible, consequently, for milling machines, only rectangular configurations can be machined or for lathes only surfaces parallel or perpendicular to the spindle axis can be machined.This type of controlled motion is often referred to as linear control or a half-axis of control.Machines with this form of control are also capable of point-to-point control.The original N/C used the closed—loop system.Of the two systems, closed and open loop, closed loop is more accurate and, as a consequence, is generally more expensive.Initially, open—loop systems were used almost entirely for light-duty applications because of inherent power limitations previously associated with conventional electric stepping motors.Recent advances in the development of electro hydraulic stepping motors have led to increasingly heavier machine load applications.中文譯文

數(shù)控技術(shù)

數(shù)控是可編程自動化技術(shù)的一種形式,通過數(shù)字、字母和其他符號來控制加工設(shè)備。數(shù)字、字母和符號用適當?shù)母袷骄幋a為一個特定工件定義指令程序。當工件改變時,指令程序就改變。這種改變程序的能力使數(shù)控適合于中、小批量生產(chǎn),寫一段新程序遠比對加工設(shè)備做大的改動容易得多。

數(shù)控機床有兩種基本形式：點位控制和連續(xù)控制(也稱為輪廓控制)。點位控制機床采用異步電動機,因此,主軸的定位只能通過完成一個運動或一個電動機的轉(zhuǎn)動來實現(xiàn)。這種機床主要用于直線切削或鉆孔、鏜孔等場合。

數(shù)控系統(tǒng)由下列組件組成：數(shù)據(jù)輸入裝置,帶控制單元的磁帶閱讀機,反饋裝置和切削機床或其他形式的數(shù)控設(shè)備。

數(shù)據(jù)輸人裝置,也稱“人機聯(lián)系裝置”,可用人工或全自動方法向機床提供數(shù)據(jù)。人工方法作為輸人數(shù)據(jù)唯一方法時,只限于少量輸入。人工輸入裝置有鍵盤,撥號盤,按鈕,開關(guān)或撥輪選擇開關(guān),這些都位于機床附近的一個控制臺上。撥號盤通常連到一個同步解析器或電位計的模擬裝置上。在大多數(shù)情況下,按鈕、開關(guān)和其他類似的旋鈕是數(shù)據(jù)輸入元件。人工輸入需要操作者控制每個操作,這是一個既慢又單調(diào)的過程,除了簡單加工場合或特殊情況,已很少使用。

幾乎所有情況下,信息都是通過卡片、穿孔紙帶或磁帶自動提供給控制單元。在傳統(tǒng)的數(shù)控系統(tǒng)中,八信道穿孔紙帶是最常用的數(shù)據(jù)輸入形式,紙帶上的編碼指令由一系列稱為程序塊的穿孔組成。每一個程序塊代表一種加工功能、一種操作或兩者的組合。紙帶上的整個數(shù)控程序由這些連續(xù)數(shù)據(jù)單元連接而成。帶有程序的長帶子像電影膠片一樣繞在盤子上,相對較短的帶子上的程序可通過將紙帶兩端連接形成一個循環(huán)而連續(xù)不斷地重復(fù)使用。帶子一旦安裝好,就可反復(fù)使用而無需進一步處理。此時,操作者只是簡單地上、下工件。穿孔紙帶是在帶有特制穿孔附件的打字機或直接連到計算機上的紙帶穿孔裝置上做成的。紙帶制造很少不出錯,錯誤可能由編程、卡片穿孔或編碼、紙帶穿孔時的物理損害等形成。通常,必須要試走幾次來排除錯誤,才能得到一個可用的工作紙帶。

雖然紙帶上的數(shù)據(jù)是自動進給的,但實際編程卻是手工完成的,在編碼紙帶做好前,編程者經(jīng)常要和一個計劃人員或工藝工程師一起工作,選擇合適的數(shù)控機床,決定加工材料,計算切削速度和進給速度,決定所需刀具類型,仔細閱讀零件圖上尺寸,定下合適的程序開始的零參考點,然后寫出程序清單,其上記載有描述加工順序的編碼數(shù)控指令,機床按順序加工工件到圖樣要求。

控制單元接受和儲存編碼數(shù)據(jù),直至形成一個完整的信息程序塊,然后解釋數(shù)控指令,并引導(dǎo)機床得到所需運動。

為更好理解控制單元的作用,可將它與撥號電話進行比較,即每撥一個數(shù)字,就儲存一個,當整個數(shù)字撥好后,電話就被激活,也就完成了呼叫。

裝在控制單元里的紙帶閱讀機,通過其內(nèi)的硅光二極管,檢測到穿過移動紙帶上的孔漏

過的光線,將光束轉(zhuǎn)變成電能,并通過放大來進一步加強信號,然后將信號送到控制單元里的寄存器,由它將動作信號傳到機床驅(qū)動裝置。

有些光電裝置能以高達每秒1000個字節(jié)的速度閱讀,這對保持機床連續(xù)動作是必須的,否則,在輪廓加工時,刀具可能在工件上產(chǎn)生劃痕。閱讀裝置必須要能以比控制系統(tǒng)處理數(shù)據(jù)更快的速度來閱讀數(shù)據(jù)程序塊。

反饋裝置是用在一些數(shù)控設(shè)備上的安全裝置,它可連續(xù)補償控制位置與機床運動滑臺的實際位置之間的誤差。裝有這種直接反饋檢查裝置的數(shù)控機床有一個閉環(huán)系統(tǒng)裝置。位置控制通過傳感器實現(xiàn),在實際工作時,記錄下滑臺的位置,并將這些信息送回控制單元。接受到的信號與紙帶輸入的信號相比較,它們之間的任何偏差都可得到糾正。

在另一個稱為開環(huán)的系統(tǒng)中,機床僅由響應(yīng)控制器命令的步進電動機驅(qū)動定位,工件的精度幾乎完全取決于絲杠的精度和機床結(jié)構(gòu)的剛度。有幾個理由可以說明步進電機是一個自動化申請的非常有用的驅(qū)動裝置。對于一件事物,它被不連續(xù)直流電壓脈沖驅(qū)使,是來自數(shù)傳計算機和其他的自動化的非常方便的輸出控制系統(tǒng)。當多數(shù)是索引或其他的自動化申請所必備者的時候,步進電機對運行一個精確的有角進步也是理想的。因為控制系統(tǒng)不需要監(jiān)聽就提供特定的輸出指令而且期待系統(tǒng)適當?shù)胤磻?yīng)的公開-環(huán)操作造成一個回應(yīng)環(huán),步進電機是理想的。一些工業(yè)的機械手使用高抬腿運步的馬乘汽車駕駛員,而且步進電機是有用的在數(shù)字受約束的工作母機中。這些申請的大部分是公開-環(huán) ,但是雇用回應(yīng)環(huán)檢測受到驅(qū)策的成份位置是可能的。環(huán)的一個分析者把真實的位置與需要的位置作比較,而且不同是考慮過的錯誤。那然后駕駛員能發(fā)行對步進電機的電脈沖,直到錯誤被減少對準零位。在這個系統(tǒng)中,沒有信息反饋到控制單元的自矯正過程。出現(xiàn)誤動作時,控制單元繼續(xù)發(fā)出電脈沖。比如,一臺數(shù)控銑床的工作臺突然過載,阻力矩超過電機轉(zhuǎn)矩時,將沒有響應(yīng)信號送回到控制器。因為,步進電機對載荷變化不敏感,所以許多數(shù)控系統(tǒng)設(shè)計允許電機停轉(zhuǎn)。然而,盡管有可能損壞機床結(jié)構(gòu)或機械傳動系統(tǒng),也有使用帶有特高轉(zhuǎn)矩步進電機的其他系統(tǒng),此時,電動機有足夠能力來應(yīng)付系統(tǒng)中任何偶然事故。

最初的數(shù)控系統(tǒng)采用開環(huán)系統(tǒng)。在開、閉環(huán)兩種系統(tǒng)中,閉環(huán)更精確,一般說來更昂貴。起初,因為原先傳統(tǒng)的步進電動機的功率限制,開環(huán)系統(tǒng)幾乎全部用于輕加工場合,最近出現(xiàn)的電液步進電動機已越來越多地用于較重的加工領(lǐng)域。