Contact Forces in Unguided Vibratory Finishing

Author(s):  
Richard Brocker ◽  
Frederik Vits ◽  
Patrick Mattfeld ◽  
Fritz Klocke

In vibratory finishing the material removal rate is influenced by the contact forces between work piece and media. In this paper a measurement system is presented which is capable of measuring the contact forces between work piece and media in unguided vibratory finishing. The unique feature of the measurement system is its completely wireless construction. The measurement results are not influenced by wires of the force sensor system including the electrical power supply and the data logging. By means of this measurement system, contact forces can be measured in unguided vibratory finishing processes for the first time. Furthermore, the influence of media size and adjustment of the unbalance motor like revolution speed, phase angle and mass distribution between the upper and the lower eccentric weight was investigated.

2015 ◽  
Vol 105 (06) ◽  
pp. 377-383
Author(s):  
F. Klocke ◽  
R. Brocker ◽  
F. Vits ◽  
P. Mattfeld

Beim Vibrationsgleitschleifen wird der Werkstoffabtrag maßgeblich durch die vorherrschenden Kontaktkräfte zwischen dem Werkstück und den Schleifkörpern bestimmt. Dieser Fachartikel stellt ein Messsystem vor, mit dem die messtechnische Erfassung der Kontaktkräfte beim ungeführten Vibrationsgleitschleifen möglich ist. Ein Alleinstellungsmerkmal ist dabei die vollständig kabellose Ausführung des Messsystems. Somit wurden die Messergebnisse nicht durch Kabel beeinflusst, die üblicherweise für die Energieversorgung und Datenübertragung notwendig sind. Mithilfe dieses Messsystems wurde der Einfluss folgender Prozesseingangsgrößen systematisch untersucht: Schleifkörpergröße, Unwuchtmotordrehzahl, Versatzwinkel der Unwuchtgewichte sowie die Masse des unteren und oberen Unwuchtgewichts auf die Kontaktkräfte.   In vibratory finishing the material removal is influenced by the contact forces between work piece and media. In this paper a measurement system is presented which is able to measure contact forces between work piece and media in unguided vibratory finishing. The unique feature of the measurement system is its completely wireless construction so that the measurement results are not influenced by wires of the force sensor system including the electrical power supply and the data logging. By means of this measurement system, contact forces can be measured in unguided vibratory finishing processes for the first time. Furthermore, the influence of media size and adjustment of the unbalance motor like revolution speed, phase angle and mass distribution between the upper and the lower eccentric weight on the contact forces was investigated.


Author(s):  
Maximilian Lachenmaier ◽  
Marius Ohlert ◽  
Daniel Trauth ◽  
Thomas Bergs

Abstract The work bowl acceleration of a vibratory finishing machine is mainly determined by the process input variables, e. g. the mass distribution between the upper and the lower imbalance weights, the offset angle between these imbalance weights and the rotational speed of the imbalance motor. The acceleration of the work bowl has a strong effect on the acceleration of the abrasive media and workpiece within the work bowl and thus on their movement. This movement indirectly determines the contact conditions, contact forces and relative velocities, between the abrasive media and the workpiece. The contact conditions have a strong effect on the material removal rate and the surface roughness of the machined workpieces in a vibratory finishing process. Due to the fact that the contact conditions can hardly be measured during the vibratory finishing process a comprehensive understanding of the transfer behavior of the work bowl acceleration on the acceleration of the abrasive media and the workpiece and thus on the prevailing contact conditions is necessary. Therefore, this publication presents an innovative approach to identify these cause-effect relationships, in order to determine the machining intensity based on the work bowl acceleration as a function of the process input variables. Hence, new measurement systems are presented which enable the determination of the acceleration of the abrasive media and the workpiece as a function of the acceleration of the work bowl of a vibratory finishing machine for the first time. Based on these investigations it is possible to identify significant areas for the work bowl acceleration, as well as for the acceleration of the abrasive media and the workpiece and thus for the contact conditions, contact forces and relative velocities, which can be used for a targeted control of the machining intensity of vibratory finishing processes.


Author(s):  
Maximilian Lachenmaier ◽  
Richard Brocker ◽  
Daniel Trauth ◽  
Fritz Klocke

The relative velocity between workpiece and media has a strong effect on the material removal rate in vibratory finishing. Due to this fact, a measurement system in the form of a camera-integrated workpiece is presented in this paper, which is capable of measuring the relative velocity between the workpiece and the media in an unguided vibratory finishing process. The unique feature of this measurement system is the completely wireless construction, so that the results are not influenced by wires for the data transfers and the electrical power supply of the light-emitting diodes of the camera system. Furthermore, the influence of the media size and adjustments of the imbalance engine like rotational speed, mass distribution between the upper and the lower imbalance weights, and offset angle between the imbalance weights were investigated. The evaluation of the results has shown that the media size and the rotational speed of the imbalance engine are the major influence factors on the relative velocity between workpiece and media.


Author(s):  
Ben Jin Wong ◽  
Ketav Majumdar ◽  
Kunal Ahluwalia ◽  
Swee-Hock Yeo

Previous work on vibratory finishing has led to a better understanding and establishment of the mass finishing processes. Despite the sustained efforts made to date, vibratory finishing remains a field where the findings made have been based largely on empirical evidence. Through force sensor analyses and scanning electron microscopy imaging, in this work a successful attempt has been made in uncovering the underlying science—through first principles of Newtonian physics—behind vibratory finishing, providing explanations for the observations made. Trials were carried out in a high-frequency vibratory bowl, the first of its kind in the vibratory finishing industry. Through these trials, mathematical formulations have been derived, essentially providing a reliable way for the industry to estimate the process cycle time.


2021 ◽  
Vol 11 (2) ◽  
pp. 466
Author(s):  
Włodzimierz Kęska ◽  
Jacek Marcinkiewicz ◽  
Łukasz Gierz ◽  
Żaneta Staszak ◽  
Jarosław Selech ◽  
...  

The continuous development of computer technology has made it applicable in many scientific fields, including research into a wide range of processes in agricultural machines. It allows the simulation of very complex physical phenomena, including grain motion. A recently discovered discrete element method (DEM) is used for this purpose. It involves direct integration of equations of grain system motion under the action of various forces, the most important of which are contact forces. The method’s accuracy depends mainly on precisely developed mathematical models of contacts. The creation of such models requires empirical validation, an experiment that investigates the course of contact forces at the moment of the impact of the grains. To achieve this, specialised test stations equipped with force and speed sensors were developed. The correct selection of testing equipment and interpretation of results play a decisive role in this type of research. This paper focuses on the evaluation of the force sensor dynamic properties’ influence on the measurement accuracy of the course of the plant grain impact forces against a stiff surface. The issue was examined using the computer simulation method. A proprietary computer software with the main calculation module and data input procedures, which presents results in a graphic form, was used for calculations. From the simulation, graphs of the contact force and force signal from the sensor were obtained. This helped to clearly indicate the essence of the correct selection of parameters used in the tests of sensors, which should be characterised by high resonance frequency.


2015 ◽  
Vol 813-814 ◽  
pp. 634-640
Author(s):  
N.K. Francis ◽  
K.G. Viswanadhan ◽  
M.M. Paulose

Swirling Fluidized Bed Polishing (SFBP) is a non–traditional alternative abrasive flow surface finishing form of Fluidized Bed Machining (FBM) in which the former has special features to overcome certain significant limitations of the latter, namely the variation of the surface roughness vertically along the component surface and the screening effect owing to the complex contours in the work piece geometry. Owing to its ability to perform machining and generate polished surface from a roughness value of Ra 1.2μ to 0.2 μ within 8 hours of processing, this new method offers greater scope in the surface modification of rough machined surfaces with complex geometry such as component with ducts and grooves. This research focus on investigating the effect of abrasive particle concentration on metal removal rate per unit area of the specimen surface. 3D surface morphology analysis investigates the quality of the polished surface and the study of circumferential uniformity and machining accuracy analysis on a complex-contoured component further investigate its scope and relevance in industrial applications.


2018 ◽  
Vol 41 (4) ◽  
pp. 1149-1159
Author(s):  
Yonghua Lu ◽  
Jing Li ◽  
Xiang Zhang ◽  
Yang Li

For measuring the thrust of combined nozzles in satellite thruster with a small space, the test method that the nozzle directly sprays on the load baffle is employed in this paper. The key problem is how to design the positions of 10 load baffles and how to construct the measurement system. A set of complete and automatic nozzle thrust measurement system is designed and built, and the influence of the load baffle applied on the flow field of nozzles is analyzed using the software FLUENT. Furthermore, the load surface locations of the sensors for the different types of nozzles are analyzed. We draw the conclusion that the load baffle position should range from 4–8 mm for the I-type nozzle and range in 6–12 mm for II-type and III-type nozzle. The correction coefficients of the thrust forces for all channels of the measurement system are determined in the calibration experiment. The uncertainty of measurement system is estimated and the error source of the measurement system is traced. We found that the systematic uncertainty is mainly contributed by the A-type uncertainty which is related with the nozzle dimension and its inner structure. The B-type uncertainty of system is contributed by the force sensor.


2020 ◽  
Author(s):  
Mark Brinton ◽  
Elliott Barcikowski ◽  
Tyler Davis ◽  
Michael Paskett ◽  
Jacob George ◽  
...  

AbstractThis paper describes a portable, prosthetic control system for at-home use of an advanced bionic arm. The system uses a modified Kalman filter to provide 6 degree-of-freedom, real-time, proportional control. We describe (a) how the system trains motor control algorithms for use with an advanced bionic arm, and (b) the system’s ability to record an unprecedented and comprehensive dataset of EMG, hand positions and force sensor values. Intact participants and a transradial amputee used the system to perform activities-of-daily-living, including bi-manual tasks, in the lab and at home. This technology enables at-home dexterous bionic arm use, and provides a high-temporal resolution description of daily use—essential information to determine clinical relevance and improve future research for advanced bionic arms.


2014 ◽  
Vol 592-594 ◽  
pp. 516-520 ◽  
Author(s):  
Basil Kuriachen ◽  
Jose Mathew

Micro EDM milling process is accruing a lot of importance in micro fabrication of difficult to machine materials. Any complex shape can be generated with the help of the controlled cylindrical tool in the pre determined path. Due to the complex material removal mechanism on the tool and the work piece, a detailed parametric study is required. In this study, the influence of various process parameters on material removal mechanism is investigated. Experiments were planned as per Response Surface Methodology (RSM) – Box Behnken design and performed under different cutting conditions of gap voltage, capacitance, electrode rotation speed and feed rate. Analysis of variance (ANOVA) was employed to identify the level of importance of machining parameters on the material removal rate. Maximum material removal rate was obtained at Voltage (115V), Capacitance (0.4μF), Electrode rotational Speed (1000rpm), and Feed rate (18mm/min). In addition, a mathematical model is created to predict the material removal


Author(s):  
Milan Kumar Das ◽  
Tapan Kumar Barman ◽  
Prasanta Sahoo ◽  
Kaushik Kumar

Conventional machining becomes non-efficient and non-effective in case of intricate shape and also while working with hard metals and alloys due to excessive tool wear. In such situations non-conventional machining, in contrast becomes more appropriate due to non-contact between tool and work-piece. In the present study, EN31 steel was machined using Plasma Arc Cutting with pre-defined process parameters. Material Removal Rate and Surface roughness were considered as responses for the study. The responses were optimized both as single and multi-response. Considering the complexities of this present problem, experimental data were generated and the results were analyzed by using Taguchi, Grey Relational Analysis and Artificial Bee Colony (ABC) Algorithm. Responses variances with the variation of process parameters were thoroughly studied and analyzed and ‘best optimal values' were identified. The result were verified by the morphological study. It was observed that there was an improvement in responses from mean to optimal values of process parameters.


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