|
|
| |
|
| |
Kinematic optimization of ball-screw transmission mechanisms
Abstract :
The paper proposes a method for the kinematic optimization of transmission mechanisms, where non-circular (NC) gears are used to perform a mechanical control on the output motion. The investigation presented here deals with the motion control of a ball-screw transmission mechanism. The objective is lowering the peak acceleration value of the screw, by designing a pair of variable radius gears as a driving mechanism. The kinematic characteristics of the ball-screw mechanism are analyzed by means of non-dimensional motion equations in order to formulate the optimization problem. A genetic algorithm (GA) is then implemented to optimize the objective function, and a penalty method is used to fulfil thedesign rules. The kinematic analysis of the optimal mechanism revealed a 37% reduction of the peak acceleration of the screw in comparison with a constant pitch screw, operated at a constant speed. A kinematic simulation is used to validate the method.
Source : www.sciencedirect.com
 پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
 جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
 Download
 منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
A ballscrew drive mechanism with piezo-electric nut for preload
and motion control
Abstract :
This work reports the development of a ballscrew drive mechanism equipped with a piezo-electric nut for active ballscrew preload and fine motion control. This mechanism is intended for a motion stage of long-stroke, high-speed and ultra-precision applications. Motion of the piezo-electric nut ballscrew drive system consists of a high-speed coarse positioning and an ultra-fine positioning. Coarse positioning is done by a conventional servo motor and ballscrew where the piezo-electric nut exerts a light ballscrew preload in order to reduce the friction torque and wear at high speed motion. After the coarse positioning, a fine position adjustment is actuated by three piezo-electric actuators to get very precise positioning. Test results show that the positioning error can be fine-adjusted to the nanometer level. The low speed stability of the ballscrew drive mechanism has also been improved using the piezo-electric actuators by applying a dither signal to the ballscrew preload. The dither action can smooth and reduce the ballscrew friction force and consequently reduce the stick–slip phenomenon at low speed motion.
Keywords: Ultra-precision positioning; Ballscrew preload control; Piezo-electric actuator
Source : www.sciencedirect.com
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
A new method and instrument for measuring circular motion error of NC machine tools
Abstract :
A new method and instrument for measuring circular motion error of numerical control (NC) machine tools are described in this paper. The instrument consists of a linear displacement transducer bar with two balls at each end and a high accuracy rotary encoder. The radius variations are detected by the transducer and the rotation angle of the bar is measured by the rotary encoder while the machine is moving in a circular path. The measuring area is circular except for a small area around the center of the disc. The bar can be expanded and contracted along its axis for different application. The instrument has a compact structure and can be installed on a machine tool simply and quickly. It is shown by the experimental results that the instrument has good repeatability and high precision of measuring circular motion trajectories. The instrument can be widely used especially in the error-compensation and error-source project in the industrial application.
Keywords : NC machine tool; Motion error; Measurement instrument; Circular measurement
Source : www.sciencedirect.com
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
Method for the evaluation of optical encoders performance under vibration
Abstract :
Optical encoders are the preferred choice for position measurement, both linear and angular, when high accuracy is required. Their performance is widely affected by deformation, temperature and vibration. This last aspect is analysed, showing the limitations found in conventional methods of performance evaluation. The determining parameters, such as sweep type, sampling rate, trigger etc. are examined and a final diagram of measuring accuracy versus frequency is presented, where aspects as resonance effects and measuring uncertainty are identified and discussed. Experimental analyses have been made in a commercial linear optical encoder and show that its measuring error is three times its precision, and wide areas of large measuring uncertainty are present in the frequency span. The information obtained through this method can be used to improve encoder design and mounting conditions in the machine, reducing the total error.
Source : www.elsevier.com/locate/precision
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
Ensuring the integrity in clinching process
Abstract :
Clinching is a mechanical joining method, especially for sheet metal parts. The process is perceived as being a simple method that is based on only the accurate movement of a punch into a die. During the process, sheet metals are deformed locally without the use of any additional elements. Precisely selected tools are a requirement for an acceptable joint. The two most frequently used geometries in clinching tools are round and square. When round tools are used, the joint has a uniform shear load capacity in all the horizontal directions. Many papers have been written on the clinching process itself, including the tool geometries, parameter optimisation, joint strengths, simulation and FE analysis of the process, but few articles discuss the significance of anticipatory maintenance or continuous follow-up while using clinching in a mass-production process. This paper points out several problems encountered in the long-term use of a clinching process. Both the lack of systematic maintenance and continuous follow-up are discussed. The significance of changes in the construction are also evaluated in this presentation that is based on a real case study. This paper also offers proposals for improvements.
Source : www.elsevier.com/locate/jmatprotec
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
Design, manufacture, stress analysis, and experimental tests of low-noise high endurance spiral bevel gears
Abstract :
The contents of the paper cover the design, manufacturing, stress analysis, and results of experimental tests of prototypes of spiral bevel gears with low levels of noise and vibration and increased endurance. The main goals are the improvement of the bearing contact, the achievement of a predesigned parabolic function of transmission errors, reduction of the magnitude of transmission errors as the precondition of reduction of noise and vibration, and avoidance of areas of severe contact stresses for the increase of the endurance of the gear drives. The goals are achieved by application of local synthesis algorithm, tooth contact analysis, and stress analysis by application of finite element method. The proposed ideas have been proven by the manufacturing and test of prototypes of spiral bevel gear drives. An example of design and optimization of a spiral bevel gear drive for the illustration of the developed theory is represented.
Source : www.Sciencedirect.com
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
Autonomous form measurement on machining centers for
free-form surfaces
Abstract :
s at developing a measurement technique on machining centers for 3D free-form contours. An autonomous measuring principle is proposed and a prototype measuring device applicable to a machining center has been produced. In the measuring device, a laser displacement detector in a narrow range, which directly detects the distance from a point on the measured surface to the reference position of the detector output, is put together with the movable part of a linear encoder on the nut of a ball screw. A stepping motor controls the laser detector position to keep the output at the central value of the detector measuring range by driving the ball screw. Both the motor and the fixed part of the linear encoder are placed on the device base. The linear encoder detects the moving displacement of the screw nut, i.e. the position change of the laser detector. By installing the base on the spindle of a machining center and moving the table along a plane perpendicular to the spindle, the laser detector can automatically follow the contour of a work piece set on the table and measure its form along a scanning line, simultaneously. The displacement of a measured point relative to the reference position of the linear encoder output on the spindle side is just equal to the sum of the outputs of the two sensors, i.e. the laser detector and the linear encoder. Moreover, a simple experimental approach to identifying the sensing direction errors for an assembled measuring device is developed. The results of some experiments are also shown, which sufficiently demonstrate the effectiveness of the proposed inspection method and error identification approach.
Keywords: Autonomous form measurement; Free-form surface; Machining center; Measuring device; Error identification.
Source : www.sciencedirect.com
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
Precision positioning of a five degree-of-freedom
planar motion stage
Abstract :
This paper presents the development of a five degree-of-freedom (DOF) planar motion stage with an integrated surface encoder for position detection. The single-level moving element is levitated by three air-bearings without mechanical contact, and is actuated by three linear motors and three piezoelectric transducer (PZT) actuators. The three linear motors are placed on the stage base to generate movement of the stage in the XYhz directions (in-plane motion), while the three PZT actuators move the stage in the Zhxhy directions (out-of-plane motion). A surface encoder composed of three two-dimensional (2D) angle sensors and a 2D angle grid is employed as the position sensor to detect the five DOF position of the stage for feedback control. Experimental results demonstrate that the surface encoder has a resolution of 30 nm and is suitable for sub-micrometer positioning. It is also confirmed experimentally that the stage can be controlled independently in the five DOFs with a positioning
resolution of 50 nm and a settling time of 50 ms.
Keywords: Five degree-of-freedom; Precision positioning; Planar motion stage; Surface encoder
Source : www.sciencedirect.com
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
Thermal analysis for the feed drive system of a CNC machine center
Abstract :
A high-speed drive system generates more heat through friction at contact areas, such as the ballscrew and the nut, thereby causing thermal expansion which adversely affects machining accuracy. Therefore, the thermal deformation of a ballscrew is one of the most important objects to consider for high-accuracy and high-speed machine tools. The objective of this work was to analyze the temperature increase and the thermal deformation of a ballscrew feed drive system. The temperature increase was measured using thermocouples, while a laser interferometer and a capacitance probe were applied to measure the thermal error of the ballscrew. Finite element method was used to analyze the thermal behavior of a ballscrew. The measured data were compared with numerical simulation results. Inverse analysis was applied to estimate the strength of the heat source from the measured temperature profile. The generated heat sources for different feed rates were investigated.
Keywords: Machine tool; Ballscrew; Thermal error; Finite element method; Thermocouple
Photograph of machine center
Source : www.sciencedirect.com
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
A new linear encoder-like capacitive displacement sensor
Abstract :
In this paper, a new encoder-like capacitive sensor filled with dielectric material is proposed for measuring relatively long range displacements with high accuracy regardless of the gap alignment of the sensor. The proposed sensor consists of two plates with zigzag-shaped electrodes coated with thin dielectric films. When one substrate slides over the other, long range displacements can be measured with high accuracy because variation in the capacitance in one period is measured with high accuracy and repeated signals are counted, as is done in linear encoders. Moreover, the thin and uniform nature of the dielectric layer on each sensor plate means that the proposed sensor is highly sensitive and stable against misalignments such as tilting. Through experimental tests, it is demonstrated that the proposed sensor can measure displacements of up to 20 mm with a resolution of about 126 nm.
Keywords: Contact-type; Capacitive displacement sensor; Encoder; Long-ranged
Source : www.sciencedirect.com
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
A validated model for the prediction of rotor bar failure in
squirrel-cage motors using instantaneous angular speed
Abstract :
Instantaneous angular speed (IAS)-based condition monitoring is an area in which significant progress has been achieved over the recent years. This condition monitoring technique is less known compared to the existing conventional methods. This paper presents model-predicted simulation and experimental results of broken rotor bar faults in a threephase induction motor using IAS variations. The simulation was performed under normal, and a broken rotor bar fault. The present paper evaluates through simulating and measuring the IAS of an induction motor at broken rotor bar faults in both time and frequency domains. Experimental results show a good agreement with the model-predicted simulation results. Three vital key features were extracted from the angular speed variations. One feature is the modulating contour of pole pass frequency periods in time domain. The other two features are in frequency domain. The primary feature is the presence of the pole pass frequency component at the low-frequency region of the IAS spectrum. The secondary feature which are the multiple of pole pass frequency sideband components around the rotor speed frequency component. Experimental results confirm the validity of the simulation results for the proposed method. The IAS has demonstrated more sensitivity than current signature analysis in detecting the fault. This research also shows the power of angular speed features as a useful tool to detect broken rotor bar deteriorations using any economical transducer such as low-resolution rotary shaft encoders; which may well be already installed for process control purposes.
Keywords: Instantaneous angular speed (IAS); Condition monitoring; Induction motor; Broken rotor bar fault; Pole pass frequency; Modulation
Source : www.sciencedirect.com
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
Spindle rotary position estimation for fast tool
servo trajectory generation
Abstract :
In diamond turning of non-rotationally symmetric surfaces, fast tool servo (FTS) trajectory is generated in real time based on the spindle rotation angle. Essentially, a digital rotary encoder updates its output (samples the spindle angle) at fixed rotary angle interval. In time domain, the encoder sampling frequency is different from that of the FTS control computer. Without proper spindle position estimation, this asynchronous nature between the encoder spatial sampling and the computer temporal sampling can cause significant amount of aliasing noise in the generated trajectory. In this paper, we first analyze this aliasing phenomenon using discrete-time signal processing theories. Based on this analysis, a spindle rotary position estimator is designed to improve both accuracy and resolution of the spindle angle feedback. Its effectiveness and the associated trajectory generation are experimentally verified in diamond turning of sinusoidal surfaces with ultra-FTS.
Keywords: Spindle angle estimation; Trajectory generation; Fast tool servo; Diamond turning
Source : www.sciencedirect.com
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
Download
منبع۱ و منبع ۲
|
|
| |
|
|
| |
|
| |
|
مطالبی راجع به هیدرولیک
|
|
پمپ به عنوان قلب سیستم هیدرولیک، توان مکانیکی را که بوسیله موتورهای الکتریکی یا احتراق داخلی تامین می گردد به توان هیدرولیکی تبدیل می کند. پمپ فقط مولد جریان سیال بوده و سطح فشار ایجاد شده به میزان بار مقاومی که توسط عملگر سیستم هیدرولیک بر آن غلبه ميشود، بستگی دارد. |
|
پمپ جابجايي مثبت به ازاء هر دو ر چرخش محور پمپ ،مقدار مشخصي از سيال را به سيستم هيدروليك ارسال مينمايد. پمپ جابجائی مثبت (دبی ثابت و متغییر ) شامل انواع پمپ دنده ای ، پره ای و پیستونی محوری و شعاعی ميباشد.
 |
 |
| پمپ پيستوني |
پمپ پره اي | |
|
در انتخاب پمپهاي با جابجايي ثابت موارد ذيل بايد در نظر گرفته شود: | |
-
قطر دهانه هاي پمپ
-
فشار كاري در خروجي پمپ
-
فشار كاري در ورودي پمپ
-
سرعت دوران پمپ
-
حجم جابجايي روغن
-
دبي موثر
-
توان موتور محرك پمپ
-
دماي كاري روغن
-
درجه ويسكوزيته
-
فيلتراسيون |
| |
|
|
| |
|
|
| |
|
| |
زبان تخصصی رشته مکانیک ساخت وتولید
ENGLISH for the student of Mechanical Engineering .....
اولین و تنها نسخه کتاب الکترونیک زبان تخصصی برای دانشجویان رشته ساخت و تولید.
تالیف : جمال الدین جلالی پور (انتشارات سمت)
توسط این کتاب الکترونیک که بصورت text تهیه شده شما میتوانید متن مورد نظر خود را توسط Narcis ویا Babylone به فارسی ترجمه کنید. لازم به ذکر است که حجم فایل نسبتا کم است.
پسورد: www.irmechanic.com يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک مستقیم می باشد .
دانلود با حجم 3.91 مگابایت
لینک منبع
|
|
| |
|
|
| |
|
| |
کتاب و حل المسائل ریاضات توماس
کتاب ریاضات توماس
زبان اصلی- هر سه جلد بصورت یکجا در یک جلد- بصورت کاملا رنگی و با کیفیت بالا - حجم ۲۱.۳ مگ بصورت PDF
حل المسائل توماس
زبان اصلی- هر سه جلد بصورت یکجا در یک جلد- بصورت کاملا رنگی و با کیفیت بالا - حجم ۱۰.۶ مگ بصورت DJUV file
نکته : فرمت DJVU یک نوع تکنولوژی پیشرفته فشرده سازی صفحات و متون اسکن شده است که کاری همانند PDF را در سطحی بالاتر انجام می دهد.اگر کتاب، مقاله یا نقشه ای با این فرمت دارید برای استفاده از آن می توانید از نرم افزارDJVU reader استفاده نمایید که از لینک زیر به صورت رایگان قابل دانلود است. (حجم: ۴۹/۶مگا بایت).
پسورد: twilightzone يا www.manufacturemajlesi.blogfa.com
جهت استفاده از مقاله به برنامه Adobe Acrobat Reader نیاز دارید.
نظر خود را در مورد این پست حتما بیان بفرمایید .
لینک غیر مستقیم و مستقیم می باشد .
دانلود کتاب دانلود حل المسائل دانلود DJVU_reader
منبع
|
|
| |
|
|
|
بسم ا.. النازل الحدید
به مدد او ، که هـــــــــر چه داریم خواست او و هــر آنچــــــه نداریم مصلحت اوست.
=======================
زکات علم به نشر آن است.
حضرت علی (ع) :
=======================
این سایت توسط جواد محمدی دانشجوی (کارشناسی ناپیوسته) مهندسی تکنولوژی ساخت و تولید دانشگاه شهر مجلسی پشتیبانی می شود.
=======================
این سایت با هدف آشنایی بازدیدکنندگان خود در تمامی زمينه های مکانيک ( اعم از ساخت و تولید ، تاسيسات ، صنايع فلزي ، متالوژی ، خودرو ، ماشين سازي ، طراحي مهندسي ،سیالات ، جامدات ، مواد ، و ... ) و ارائه مطالب آزاد علمی و مهندسی جمع آوری شده از مقالات ، پایان نامه ها ، کتب ، اساتید ، همایش ها و سایت های اینترنتی معتبر فعالیت می کند.
مطالب ، مقالات ، برنامه های خود را راجع به موضوعات سایت را به ایمیل ما و هرگونه انتقاد ، پیشنهاد و سوالات خود رادر بخش نظرات ارسال کرده که مورد برسی قرار گیرد . منتظر نظرات شما هستم.
=======================
نکته بسیار بسیار مهم : پست های این سایت از منابع گوناگونی جمع آوری شده اند که برخی از آنها منبع اونها نامعلوم می باشد . ضمنا مطالب آذر ماه 87 به بعد تمامی منابع اونها ذکر می شود و اگر شخصی اعتراضی نسبت به مطلبی داشت در قسمت نظرات بگوید تا ما منبع اون رو قرار داده و یا حتی اون مطلب را حذف کنیم پش حتما در صورت نا رضایتی حتما ما را آگاه کنید تا لینک حذف شود و یا منبع قرار گیرد و به تمامی اعتراضات رسیدگی می شود .
=======================
برای جستجوی بهتر و دسترسی به تمامی مطالب ما به آرشیو موضوعی سایت که سمت راست صفحه قرار دارد مراجعه کنید.
=======================
برخی از مقالات ، پایان نامه ها ، برنامه ها و پسورد برنامه ها و ... را فقط برای اعضای خبر نامه سایت فرستاده می شود پس لطفا در خبرنامه حتما عضو شوید تا مطالب خاص برای شما فرستاده شود.
=======================
آماده تبادل لینک با تمامی وبلاگ ها و وبسایت ها هستیم و در صورت لزوم لطفا لینک ما را با نام مهندسی مکانیک ساخت و تولید قرار دهید و ما را خبر کنید تا لینک شما هم قرار گیرد.
=======================
و در آخر : مکانيک زندگی
ای کاش یاد بگیریم ، که زیر بارهای خمشی و پیچشی زندگی نقطه تسلیم را بالا بگیریم و مقاومت شکست را حداکثر کنیم تا چرخ دنده های زندگیمان از لهیدگی و تداخل در امان باشد.
" طراحی اجزا ماشین" نوشته "جوزف شیگلی" !!!.
=======================
در سيال زمان در گذرم
در پيچ، پيچ پيچها مي پيچم
در محبت جوش مي خورم
ودرغلتش زمان مي لغزم
در روح بي نهايت و تا ابد اشباع نشده دنبال چيزي مي گردم.
در برابرغم هايم
چون بتن قرن مي مانم و
چرخدنده ي ذهنم شفت قدمهايم را با گشتاور عشق مي راند.
در دايره ي گام چرخدنده ي زندگي ام، چون يك پيستون
تا نقطه ي مرگ پيش مي روم .
تسمه و زنجيري از جنس دلبستگي
مرا دلبسته ي اين روز ها مي كند.
دنيا مرا آزرده اما
ضريب ايمني در برابر خستگي هايم به بي نهايت مي رسد .
در چرخش ثانيه هاي غم
روحم ترك خورد؛
اما تمركز هيچ تنشي نمي تواند مرا بشكند ،
چون خدا را دارم...
|
