Chatter Suppression via an Oscillating Cutter

1999 ◽  
Vol 121 (1) ◽  
pp. 54-60 ◽  
Author(s):  
F. Yang ◽  
B. Zhang ◽  
J. Yu
Keyword(s):  
Experimental Studies ◽  
Rake Angle ◽  
Transmission Mechanism ◽  
Machining Process ◽  
Chatter Suppression ◽  
Critical Issues ◽  
The Stability ◽  
Cutting System ◽  
Theoretical Analyses

Chatter is one of the critical issues in a machining process since it deteriorates the surface quality of a workpiece and reduces machining efficiency. A new method is developed to suppress chatter in which an oscillating cutter is used to machine the workpiece through a stepping motor and a transmission mechanism so as to vary tool rake angle continuously and periodically in process. Theoretical analyses are performed on the stability of the cutting system, and verified by the experimental studies. Both theoretical analyses and experimental results indicate that the method can suppress chatter in a turning process effectively. With the application of an oscillating cutter, the amplitude can be reduced by 80 percent in cutting a steel workpiece.

Analytical and experimental stability analysis of AU4G1 thin-walled tubular workpieces in turning process

2020 ◽  
Vol 234 (6-7) ◽  
pp. 1007-1018 ◽  
Author(s):  
Zied Sahraoui ◽  
Kamel Mehdi ◽  
Moez Ben-Jaber
Keyword(s):  
Stability Analysis ◽  
Feed Rate ◽  
Experimental Studies ◽  
Rake Angle ◽  
Machining Process ◽  
Structural Damping ◽  
Turning Process ◽  
Process Stability ◽  
Thin Walled ◽  
The Stability

The development of the manufacturing-based industries is principally due to the improvement of various machining operations. Experimental studies are important in researches, and their results are also considered useful by the manufacturing industries with their aim to increase quality and productivity. Turning is one of the principal machining processes, and it has been studied since the 20th century in order to prevent machining problems. Chatter or self-excited vibrations represent an important problem and generate the most negative effects on the machined workpiece. To study this cutting process problem, various models were developed to predict stable and unstable cutting conditions. Stability analysis using lobes diagrams became useful to classify stable and unstable conditions. The purpose of this study is to analyze a turning process stability using an analytical model, with three degrees of freedoms, supported and validated with experimental tests results during roughing operations conducted on AU4G1 thin-walled tubular workpieces. The effects of the tubular workpiece thickness, the feed rate and the tool rake angle on the machining process stability will be presented. In addition, the effect of an additional structural damping, mounted inside the tubular workpiece, on the machining process stability will be also studied. It is found that the machining stability process is affected by the tubular workpiece thickness, the feed rate and the tool rake angle. The additional structural damping increases the stability of the machining process and reduces considerably the workpiece vibrations amplitudes. The experimental results highlight that the dynamic behavior of turning process is governed by large radial deformations of the thin-walled workpieces. The influence of this behavior on the stability of the machining process is assumed to be preponderant.

Chatter Suppression With Multiple Time-Varying Parameters in Turning

1999 ◽  
Author(s):  
Fulun Yang ◽  
Bi Zhang ◽  
Junyi Yu
Keyword(s):  
Rake Angle ◽  
Machining Process ◽  
New Method ◽  
Multiple Time ◽  
Time Varying ◽  
Varying Parameters ◽  
Chatter Suppression ◽  
Time Varying Parameter ◽  
Time Varying Parameters ◽  
Theoretical Analyses

Abstract This paper presents a new method, multiple time-varying parameter (MTVP) turning for chatter suppression. Compared to the single time-varying parameter (STVP) turning, the new method uses both time-varying spindle speed and time-varying rake angle to suppress chatter. The paper provides theoretical analyses on the MTVP turning and experimental results to justify the analytical results. It compares the effects of chatter suppression between the MTVP and STVP turnings, and discusses the possible mechanisms of chatter suppression. The paper then concludes that the MTVP turning method is more effective in chatter suppression than the STVP turning method because of the combined effect of the multiple time-varying parameters. It is demonstrated that the MTVP turning method can suppress chatter by 80%, and can be applied to suppress all kinds of chatter in a machining process.

Global Configuration Design of Umbilicals in Deepwater

2005 ◽  
Author(s):  
Ray Fleming ◽  
Thanos Moros ◽  
Rupak Ghosh ◽  
Kostas Lambrakos ◽  
Dave Robson
Keyword(s):  
Configuration Design ◽  
Loop Current ◽  
Global Configuration ◽  
Critical Issues ◽  
The Stability ◽  
Heave Motion ◽  
Vessel Motion ◽  
And Control ◽  
Selection Of

Global configuration design of subsea umbilical risers in deep water is a major challenge due to extreme environmental and operational requirements. The critical issues considered in design are the interference between umbilicals in the presence of strong loop and submerged current, and the on-bottom stability along with the strength and fatigue requirements. The vessel motion primarily controls the selection of the configuration, catenary or lazy wave, and the latter is an obvious choice in the presence of significant heave motion. The length and routing on the seabed ensures the on-bottom umbilical stability by dissipating the axial load through soil friction. However, the interference with other subsea components as well as the space availability can also be a governing criterion in the routing. Finally, all these design requirements must be satisfied economically from the perspective of overall cost of the project without compromising quality of the product and safety of design. This paper presents a brief outline of the global configuration design of umbilicals accounting for various design considerations. The host is a semi submersible in a water depth of 6050-ft in the Gulf of Mexico. The lazy wave configurations of the chemical injection and control umbilicals are considered for the study presented herein. The methodology of design for the global configuration is discussed considering different environmental loadings such as the 100-yr and 10-yr loop current, and 100-yr submerged current. The stability of the umbilical on the seabed is discussed on the basis of analysis results for the environmental loadings with dominant vessel motions. The phenomenon of “walking” under the influence of dynamic loading is investigated and the necessary considerations in design to prevent the umbilicals from “walking” are also discussed.

scholarly journals INVESTIGATION OF THE INFLUENCE OF PRESSING BELTS TENSION OF THE BACK CIRCUIT OF PRESS - SELECTIVE PR-1.5

2018 ◽  
Vol 13 (2) ◽  
pp. 76-76
Author(s):  
Валерий Белов ◽  
Valeriy Belov ◽  
Леонид Рыбаков ◽  
Leonid Rybakov ◽  
Светлана Овчукова ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Experimental Studies ◽  
Field Research ◽  
Test Protocol ◽  
Optimal Value ◽  
The Stability ◽  
The Moment ◽  
The Mathematical Model ◽  
Elastic Characteristics

A brief analysis of suspension mechanisms and ways to improve the quality of press harvesting for flax harvesting is considered. By researching the mathematical model, the authors prove the possibility of increasing the stability of the elastic characteristics of the suspension mechanisms by changing the angle between the levers or changing the geometry of the structure, for example, the attachment point of a two-arm lever. Particular attention is drawn to the new term “reduced rigidity” of the suspension mechanism. Using this notion and the method of its determination, the authors recommend determining the optimal value of the reduced stiffness of the suspension in the way of mathematical modeling and using this indicator as the main optimization parameter. The results of theoretical and experimental studies were presented by the authors in the form of elastic characteristics of the suspension mechanisms. When conducting a study of the mathematical model, it is suggested to take into account the condition of equality of the maximum values of the moments of forces from the action of the tension forces of the belts or the mass of the working element and the moment of forces acting on the side of the tension springs. During the research of the suspension mechanism, the actual dimensions of the PR-1.5 baler design were adopted. At the same time, we briefly describe the design of the improved tensioning mechanism of a baler for flax harvesting. A rather detailed analysis is given by the authors of the obtained elastic characteristics of the suspension mechanism. Some new features of the elastic characteristics of the suspension mechanism that have not been previously detected are described. To confirm the correctness of the reasoning, the authors implemented their research in a real press-picker and conducted field research that confirmed the possibility of improving the quality of the upgraded version of the machine. To confirm the results of the research, the authors presented a fragment of the field test protocol. The task is solved, uniformity of the roll density is ensured and its density is increased.

scholarly journals IMPROVEMENT OF THE STRUCTURAL LAYOUT OF POTATO PLANTERS’ COULTER GROUP

2021 ◽  
pp. 81-90
Author(s):  
Alexey Semenovich Dorokhov ◽  
Andrey Grigoryevich Ponomarev ◽  
Vitaly Nikolaevich Zernov ◽  
Sergey Nikolaevich Petukhov ◽  
Alexander Gennadievich Aksenov ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Acute Angle ◽  
Sharp Angle ◽  
Maximum Extent ◽  
Automatic Maintenance ◽  
Potato Planter ◽  
Growing Conditions ◽  
The Stability ◽  
The Impact

Structural layouts of coulters and their groups in potato planters are justified in the article based on the morphological features of the potato plant, its requirements for growing conditions and ensuring the quality of the planting process. The purpose of coulter groups is to form a bed for placing tubers with a loose layer of soil in 5-8 cm and sealing them with loosened soil to a certain depth. To substantiate the type of potato planter coulters that meet the requirements for potato growing conditions to the maximum extent possible, optimize the parameters of coulter groups that automatically ensure the stability of the coulter travel depth when imitating irregularities of the field microrelief. A comparative analysis of the impact on the soil of the most common anchor coulters with a blunt angle of soil entry and a sharp angle with an individual floating suspension is given, and indicators of the quality of their operation are described. It was found that coulters with an individual floating suspension and an acute angle of soil entry meet the requirements for potato growing conditions to the maximum extent possible. In order to ensure travel stabilization of such a coulter at a given depth when imitating field irregularities, a version of the coulter group has been developed that provides automatic correction of the coulter's angle of attack when changing its travel depth. Experimental studies have optimized the parameters of the coulter suspension that ensure automatic imitation of field microrelief irregularities up to 20 cm deep within the initial requirements for potato planting machines. Coulters with an individual floating suspension and a sharp angle of soil entry most fully meet the requirements for potato growing conditions to the maximum extent possible. A coulter group with a suspension aspect ratio of 150:200:400:400 cm and an acute angle of coulter entry into the soil provides automatic maintenance of the set coulter travel depth within the initial requirements (±2 cm) for irregularities in the field microrelief of up to 200 mm. In this case, the bottom and walls of the furrow are not compacted.

The Monitoring System for Stability of CNC Machining Based on cDAQ and LabVIEW

2014 ◽  
Vol 1039 ◽  
pp. 177-182
Author(s):  
Man Meng ◽  
Wen Jun Zhang ◽  
Peng Chong Wang ◽  
Denis Niedenzu ◽  
Ying Zhong Tian
Keyword(s):  
Monitoring System ◽  
Online Monitoring ◽  
Cnc Machining ◽  
Machining Process ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Online Monitoring System ◽  
Main Factors ◽  
The Stability

In recent years, researching the stability of the CNC machining process is a hotpot in CNC industry. Based on cDAQ and labVIEW, online monitoring system is presented, meanwhile, both software structure and hardware structure are introduced in detail. Researches show that vibration and pressure are the main factors for the quality of the flatness. By studying the relative vibration between the spindle and the platform in the Z axis direction, as well as the shifty pressure that tool works on the flatness of the workpiece, four experiments are designed in this paper under different technological conditions including free moving, Axial Depth of cut, speed and feed speed, which verify the reliability of the online monitoring system.

scholarly journals Decomposition of milling operation

2018 ◽  
Vol 224 ◽  
pp. 01136
Author(s):  
Yurij Novoselov ◽  
Mariya Piankovskaya ◽  
Vladimir Bogutsky
Keyword(s):  
Machine Tool ◽  
Contact Zone ◽  
Block Diagram ◽  
Quality Parameters ◽  
Machining Process ◽  
Milling Operation ◽  
The Stability ◽  
Main Components ◽  
The Relationship

The article deals with the problem of improving the stability of quality parameters in the milling of molds, which provides for minimizing deviations from the set values that meet the requirements of the product drawing. For this purpose, a block diagram of the milling operation was developed and decomposition was carried out, which allowed to identify such subsystems, “workpiece”, “machine — tool”, “tool”, “contact zone”. The factors that lead to a decrease in the parameters of the quality of the surfaces of the workpiece are determined. The developed block diagram allowed to establish the relationship between the main components of the technological system and the characteristics of the machining process.

scholarly journals Dynamic Modeling and Cutting Stability of Rotating Tapered Composite Cutter Bar considering Material Damping

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yuhuan Zhang ◽  
Ren Yongsheng ◽  
Bole Ma ◽  
Jinfeng Zhang
Keyword(s):  
Constitutive Relations ◽  
Equations Of Motion ◽  
Beam Theory ◽  
Chatter Stability ◽  
Differential Motion ◽  
Chatter Suppression ◽  
Fixed Type ◽  
The Stability ◽  
The Galerkin Method ◽  
Cutting System

Traditional milling cutter bars are generally made up of metals and exhibit poor capacity of chatter suppression. This study proposes an anisotropic composites tapered cutter bar for increasing natural frequency and damping and finally achieves the goal of enhancing chatter stability. Based on Hamilton principle and Euler–Bernoulli beam theory, the partial differential motion equations of the cutting system with a 3D rotating tapered composite cutter bar are established. Next, using the Galerkin method, the equations of motion are discretized so as to derive ordinary differential equations. In the model, damping modeling of the composite cutter bar is achieved theoretically by using damping dissipation constitutive relations for viscoelastic composites. Moreover, by introducing the rotating effect of the 3D cutter bar in the 2-DOF analytical model of stability analysis first proposed for a fixed-type cutter bar, an improved prediction model is developed and used to solve the stability lobes of the cutting system in the frequency domain analytically. Furthermore, the influences of the gyroscopic effect, material, ply angle, stacking sequence, and taper ratio on chatter stability are also discussed.

Synergetic approach to improve the efficiency of machining process control on metal-cutting machines

2021 ◽  
Vol 23 (3) ◽  
pp. 84-99
Author(s):  
Vilor Zakovorotny ◽  
◽  
Valery Gvindjiliya ◽  
Keyword(s):  
Dynamic System ◽  
Internal Control ◽  
Metal Cutting ◽  
A Priori ◽  
Machining Process ◽  
External Control ◽  
Processing Efficiency ◽  
Cutting System ◽  
Required Quality

Introduction. The efficiency of processing on metal-cutting machines is evaluated by the reduced cost of producing a batch of parts while ensuring the required quality. In modern production, parts are usually made on CNC machines. Today the CNC program and the trajectories of the machine tool actuators match each other with high accuracy, which, however, does not yet guarantee quality and efficiency of production. The definition of the CNC program is based on the knowledge base of rational modes, tools, coolant and etc. during processing. This base reflects some averaging over the set of machines, tools and processing conditions, and does not take into account changes in the properties of the dynamic system in the process of cutting. Subject. The paper deals with the synergistic matching of external control (CNC programs) and cutting dynamics (internal control). The internal control factors can be set a priori, as well as determined as a result of the influence of irreversible energy transformations in the cutting zone. The purpose of the work is to determine the law of controlling the trajectories of the machine's executive elements in such a way that, with changing properties of the dynamic cutting system, the required surface quality of the part and minimizing the intensity of tool wear are ensured during the processing of the part. Method and methodology. Mathematical simulation of the controlled dynamic system, which properties change due to the a priori set laws of variation of subsystem parameters, as well as changes in the cutting properties conditioned by the power of irreversible energy transformation is presented. Consideration of the power of irreversible energy transformations is necessary for predicting back-edge wear, changes in dynamic coupling parameters, and evolutionary restructuring of cutting dynamics. Results and Discussion. The regularity of matching the CNC program with the changing properties of the cutting process, which allows increasing the processing efficiency while ensuring the required quality of parts, is disclosed. A number of properties of the dynamic cutting system caused by changing trajectory of the longitudinal feed rate of the tool during processing of the shaft, the stiffness change of which is given, are revealed and analyzed.

Dynamics of flexible detail milling

2011 ◽  
Vol 225 (4) ◽  
pp. 299-309 ◽  
Author(s):  
S A Voronov ◽  
I A Kiselev
Keyword(s):  
Milling Process ◽  
Machining Process ◽  
Machined Surface ◽  
Workpiece Surface ◽  
Thin Walled Structures ◽  
Milling Operations ◽  
Efficient Processing ◽  
The Stability ◽  
Five Axis

The five-axis milling operations are commonly used in aerospace industry. For example, this operation is the base for the machining process of the turbine blade production. The milling operations of thin-walled structures cause the vibrations of the tool and the workpiece and this turn affect the quality of the workpiece surface. Modelling of the milling process is necessary to determine the proper cutting conditions for the required productivity and the surface quality. In this article, the geometry modelling algorithm for five-axis milling process is proposed. Dynamics of the machined surface is modelled using the finite-element method. The obtained results make possible to conclude about the stability of milling process and to calculate the efficient processing conditions at which the amplitude of the generated vibrations does not exceed the admissible level. The results of this research can be used while the milling process technologies are designed. Especially, it is significant for the machining of hard-to-machine materials and processing of heat-resistant alloys in space and aircraft industries.

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