Grinding and Dressing Tools for Precision Machines

2020 ◽  
pp. 233-263
Author(s):  
Yunfeng Peng ◽  
Zhenzhong Wang ◽  
Ping Yang
Keyword(s):  
Precision Machines

SIMULATION OF THE DYNAMICS OF CASSAVA STEM CUTTINGS ON AN INCLINED WOOD SURFACE

2018 ◽  
Vol 14 (2) ◽  
pp. 85-97
Author(s):  
I A OLA ◽  
O O AREMU ◽  
A A ADERINLEWO ◽  
E S.A AJISEGIRI ◽  
P O AIYEDUN ◽  
...  
Keyword(s):  
Wood Surface ◽  
Great Influence ◽  
Stem Cuttings ◽  
Flow Properties ◽  
Angle Variation ◽  
Predictive Parameters ◽  
Major Transition ◽  
Cassava Stem ◽  
The Tropics ◽  
Precision Machines

Development of precision machines to handle some of the field activities involved in the cultivation of cassava is a highly welcomed project among young enterprising farmers who are keen in resolving the posterity of their wellbeing as a big time farmer. Mechanization of cassava in the tropics is grossly hampered by lack of extensive knowlegde on the behaviour, physical properties of cassava stems and parameters that have great influence on the handling of the stems during cultivation, hence the limita-tion of advancing the present semi-automatic planter to fully automated one is still a mirage in the tropics. This paper presents the flow properties of cassava cuttings that can lend it to proper handling in a metering machine. A variable inclined wood surface rig with an ejection outlet was used to study the properties of the stem. Measured cassava stem predictive parameters; diamater, lentgh,weight; angle variation on the rig; response parameters; percentage ejected, percentage sliding through, forces acting on stems were obtained. The results from the study could be used to predict acurately the exact dynamics of a given stem isolated from the bulk of stem cuttings stacked in the metering hopper. Models to predict the flow properties of the stems were obtained; further simulation of the dynamics was embarked upon using MATLAB software. A major transition zone of stem characteris-tics per pecentage sliding to ejection occurred within the range of angles of 150 -300. This might be a favourable angular zone for isolating the stems from the bulk mass while the effectively isolated stems can be metered appropriately by another mechanism in the process of developing a metering device for cassava stem cuttings.

Air Characteristics in Air Turbine Spindle of Ultra Precision Machines

2010 ◽  
Vol 297-301 ◽  
pp. 396-401
Author(s):  
Mehrdad Vahdati ◽  
E. Azimi ◽  
Ali Shokuhfar
Keyword(s):  
High Speed ◽  
Design Procedure ◽  
Inlet Pressure ◽  
Cylindrical Shape ◽  
Air Inlet ◽  
Wind Turbine System ◽  
Air Turbine ◽  
Ultra Precision ◽  
The One ◽  
Precision Machines

Air Spindles have been used in ultra precision machines for several years due to their advantages such as high speed rotation, low friction, and low vibration, [1]. Air spindles are widely used in these machines for producing precise work pieces. Although, spindles function on a very complicated theoretical basis, [2, 3], their structure is very simple and consists of mainly a rotor and a stator. The rotor/stator could be made of different shapes. A cylindrical shape is the one commonly in use. The spindle designed in this work has a spherical configuration. It has been designed so that it could be moved without application of electric motor and only by a wind turbine system, [4]. The spindle studied in this research uses compressed air for rotor suspension, and has an air turbine for rotating its shaft. A thin air film acts as bearing layer between rotor and stator. In design procedure, operation parameters such as air inlet pressure for turbine, air inlet pressure for bearing, diameter of turbine nuzzles, diameter of bearing nuzzles, clearance between rotor and stator and etc. have been considered, [5]. A prototype spindle has been manufactured using design criteria. The influence of above mentioned parameters have been recognized through experiments.

Generalized Abbe Principle: Position Error Propagation in Machine Elements

1996 ◽  
Author(s):  
Joseph Pegna
Keyword(s):  
Error Propagation ◽  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Statistical Characterization ◽  
Physical Limit ◽  
Potential Applications ◽  
Machine Elements ◽  
Tolerance Verification ◽  
Precision Machines

Abstract In the quest for ever finer levels of technology integration, mechanical linkages reach their precision limits at about 5micrometers per meter of workspace. Beyond this physical limit, all six dimensional degrees of freedom need to be precisely ascertained to account for mechanical imperfections. This paper substantiates Wu’s vision of “precision machines without precision machinery.” A formulation and statistical characterization of position and orientation error propagation in rigid bodies are presented for two extreme models of measurement. It is shown that error distribution is uniquely dependent upon the design of the measurement plan. The theoretical foundations presented were evolved in the course of designing precision machinery. Other potential applications include: fixture design, metrology, and geometric tolerance verification.

Error Allocation in the Design of Precision Machines

2020 ◽  
pp. 207-232
Author(s):  
Shanshan Chen ◽  
Guofeng Zhang
Keyword(s):  
Precision Machines

scholarly journals Active vibration isolation of high precision machines

2010 ◽  
Vol 1 (MEDSI-6) ◽  
Author(s):  
C. Collette ◽  
S. Janssens ◽  
K. Artoos ◽  
C. Hauviller
Keyword(s):  
Active Control ◽  
High Precision ◽  
Vibration Isolation ◽  
Control Strategies ◽  
External Disturbances ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Atomic Force ◽  
Active Vibration ◽  
Precision Machines

This paper provides a review of active control strategies used to isolate high-precisionmachines (e.g. telescopes, particle colliders, interferometers, lithography machines or atomic force microscopes) from external disturbances. The objective of this review is to provide tools to develop the best strategy for a given application. Firstly, the main strategies are presented and compared, using single degree of freedom models. Secondly, the case of huge structures constituted of a large number of elements, like particle colliders or segmented telescopes, is considered.

Modelling Transient Behavior of a Mechanical System Including a Rolling and Sliding Contact

Tribology ◽  
2005 ◽  
Author(s):  
Anders So¨derberg ◽  
Christer Spiegelberg
Keyword(s):  
Contact Stiffness ◽  
Transient Behavior ◽  
Measurement Procedure ◽  
Sliding Contact ◽  
Contact Model ◽  
Test Equipment ◽  
Main Concern ◽  
Contact Conditions ◽  
Machine Elements ◽  
Precision Machines

The friction and wear of rolling and sliding contacts are critical factors for the operation of machine elements such as bearings, gears, and cam mechanisms. In precision machines, for example, the main concern is to compensate for frictional losses, so as to improve control accuracy. In other applications it is often desirable to minimize friction losses to improve efficiency, though sometimes high friction is desired to prevent sliding and wear. The aim of this study is to simulate the behavior of a test equipment and show that simulations can be used to study and optimize mechanical systems that include rolling and sliding contact. Simulations can be used to study the system as a whole, as well as the contact conditions. The test equipment and the measurement procedure used are described. In the simulations, a contact model designed to handle transient contact conditions is integrated into a system model. The results show that the contact strongly influences the system. The simulations show that the use of a contact model allows the simulation of systems that contain contacts with different amounts of slip, and that such simulations can be used to study the contact as well as the system. Surface roughness influences the contact stiffness and is included in the simulations.

Graticule Ruling in Australia

1949 ◽  
Vol 160 (1) ◽  
pp. 145-153
Author(s):  
Mansergh Shaw
Keyword(s):  
High Precision ◽  
Etching Process ◽  
The Other ◽  
Geographic Isolation ◽  
Precision Machines ◽  
Glass Blank ◽  
Complete Process ◽  
Better Than ◽  
Made In

The problems of precision manufacture in Australia, arising chiefly from her geographic isolation, are first discussed. The paper then takes one particular problem from the field of optical manufacture and shows how it was solved for the conditions prevailing in the Dominion. The problem discussed is the production of graticules, or reticles, for range-finders, predictors, gun sights, telescopes, binoculars, microscopes, collimators, and many other such instruments. The first part of the paper deals briefly with methods used in reproducing the pattern, particularly the ruling and etching process. The second, and much the larger, part of the paper deals with the design of the high precision machines which were made for ruling the glass disks preparatory to etching the pattern into the glass. Two such machines were developed, one generating the pattern from the movements of the machine itself, the other, a pantograph, by copying the pattern from master plates. A series of self-checking tests is described by which the accuracy of the generating machine could rapidly be tested to an accuracy of much better than 0·0001 inch. A brief survey of the complete process, from glass blank to finished graticule, is made in the Appendix.

Spherical surface generation mechanism in the grinding of balls for ultraprecision ball bearings

2000 ◽  
Vol 214 (4) ◽  
pp. 351-357 ◽  
Author(s):  
B Zhang ◽  
A Nakajima
Keyword(s):  
Kinematic Analysis ◽  
High Speed ◽  
Spherical Surface ◽  
Generation Mechanism ◽  
Surface Generation ◽  
Ball Bearings ◽  
Contact Points ◽  
Ball Surface ◽  
Precision Machines ◽  
Good Agreement

Ultraprecision ball bearings are necessary for high-precision machines and/or high-speed machines since the vibration caused by ball bearings determines the precision of machines as a whole and may make high-speed machines fail to work. To produce ultraprecision ball bearings, it is necessary to clarify spherical surface generation mechanism in the grinding of balls. This paper is the first attempt to investigate the contact trace distribution on the ball surface, which is crucial to spherical surface generation. The kinematic analysis of the contact trace shows that the contact trace is a fixed circle on the ball surface and the contact points are not uniformly distributed on the ball surface. Experimental observation of the contact trace was also carried out. The observation is in good agreement with the analysis. Suggestions on how to distribute the contact trace over the whole ball surface and therefore to improve the precision of balls are given.

Sign in / Sign up

Export Citation Format

Share Document