Optimal Infeed Control for Accelerated Spark-Out in Plunge Grinding

1984 ◽  
Vol 106 (1) ◽  
pp. 70-74 ◽  
Author(s):  
S. Malkin ◽  
Y. Koren
Keyword(s):  
Direct Measurement ◽  
Time Constant ◽  
Cycle Time ◽  
Characteristic Time ◽  
Control Policy ◽  
Plunge Grinding ◽  
Elastic Deflection ◽  
Time Required

An optimal infeed control policy is proposed to minimize the cycle time in cylindrical plunge grinding. As compared with conventional infeed control consisting of roughing followed by spark-out, the proposed infeed control policy accelerates the spark-out by reducing the time required to recover the accumulated elastic deflection in the system and to reduce the infeed velocity to its final required value. This optimal infeed control policy is particularly advantageous for grinding systems having a long characteristic time constant. A practial method is described for implementing the optimal infeed control policy based upon direct measurement of the radial allowance remaining on the workpiece.

Continuous Optimal Infeed Control for Cylindrical Plunge Grinding, Part 1: Methodology

2004 ◽  
Vol 126 (2) ◽  
pp. 327-333 ◽  
Author(s):  
Shaoqiang Dong ◽  
Kourosh Danai ◽  
Stephen Malkin ◽  
Abhijit Deshmukh
Keyword(s):  
Optimal Control ◽  
Dynamic Programming ◽  
Cycle Time ◽  
Optimal Policy ◽  
Controller Design ◽  
Control Policy ◽  
Active Constraint ◽  
Plunge Grinding ◽  
On Line ◽  
Sampling Instant

A new methodology is developed for optimal infeed control of cylindrical plunge grinding cycles. Unlike conventional cycles having a few sequential stages with discrete infeed rates, the new methodology allows for continuous variation of the infeed rate to further reduce the cycle time. Distinctive characteristics of optimal grinding cycles with variable infeed rates were investigated by applying dynamic programming to a simulation of the grinding cycle. The simulated optimal cycles were found to consist of distinct segments with predominant constraints. This provided the basis for an optimal control policy whereby the infeed rate is determined according to the active constraint at each segment of the cycle. Accordingly, the controller is designed to identify the state of the cycle at each sampling instant from on-line measurements of power and size, and to then compute the infeed rate according to the optimal policy associated with that state. The optimization policy is described in this paper, and the controller design and its implementation are presented in the following paper [1].

Analysis and Reduction of the Waste in the Work Process Using Time Study Analysis: A Case Study

2014 ◽  
Vol 660 ◽  
pp. 971-975 ◽  
Author(s):  
Mohd Norzaim bin Che Ani ◽  
Siti Aisyah Binti Abdul Hamid
Keyword(s):  
Cycle Time ◽  
Lean Manufacturing ◽  
Value Added ◽  
Time Study ◽  
Study Approach ◽  
Root Cause ◽  
Wide Range ◽  
Unit Of Work ◽  
Time Required ◽  
The Impact

Time study is the process of observation which concerned with the determination of the amount of time required to perform a unit of work involves of internal, external and machine time elements. Originally, time study was first starting to be used in Europe since 1760s in manufacturing fields. It is the flexible technique in lean manufacturing and suitable for a wide range of situations. Time study approach that enable of reducing or minimizing ‘non-value added activities’ in the process cycle time which contribute to bottleneck time. The impact on improving process cycle time for organization that it was increasing the productivity and reduce cost. This project paper focusing on time study at selected processes with bottleneck time and identify the possible root cause which was contribute to high time required to perform a unit of work.

DETERMINATION OF URANIUM IN FLOTATION CONCENTRATES AND IN LEACH LIQUORS BY X-RAY FLUORESCENCE

1959 ◽  
Vol 37 (1) ◽  
pp. 20-28 ◽  
Author(s):  
G. L. Smithson ◽  
R. L. Eager ◽  
A. B. VanCleave
Keyword(s):  
Direct Measurement ◽  
Pilot Plant ◽  
Internal Standard ◽  
Liquid Extraction ◽  
X Ray ◽  
Liquid Liquid Extraction ◽  
Northern Saskatchewan ◽  
Plant Operations ◽  
Time Required

X-Ray fluorescence has been applied to the analysis of flotation concentrates obtained from pegmatitic uranium ores occurring in Northern Saskatchewan. Approximate uranium analyses can be obtained by direct measurement on flotation concentrates but more accurate results are obtained by using an internal standard such as strontium or yttrium. The time required for an analysis, as compared to that of conventional chemical or fluorimetric methods, is considerably reduced and flotation pilot plant operations can therefore be more effectively controlled. The method has been extended to include the analysis of sulphate leach liquors obtained from the leaching of pegmatitic ores and their flotation concentrates. Organic phases obtained in liquid – liquid extraction studies can also be rapidly analyzed for uranium by X-ray fluorescence.

Experimental Approach for Finding the Response Time of MR Dampers for Vehicle Applications

2003 ◽  
Author(s):  
Fernando D. Goncalves ◽  
Jeong-Hoi Koo ◽  
Mehdi Ahmadian
Keyword(s):  
Response Time ◽  
Time Constant ◽  
Constant Velocity ◽  
Mr Damper ◽  
Initial State ◽  
Final State ◽  
Mr Dampers ◽  
Automotive Suspension ◽  
Magneto Rheological ◽  
Time Required

This paper offers a method and an experimental example of determining the response time of Magneto-Rheological (MR) dampers. The response time of MR dampers for automotive suspension applications is valuable information because it is one of the key factors that determine the practical effectiveness of the use of MR dampers in vehicles. However, a detailed description of the response time of MR dampers is seldom given in the literature. Furthermore, the methods of computing the response time are not discussed in detail. Therefore, this study intends to develop a method for experimental determination of the response time of MR dampers for automotive suspensions. A triangle wave that maintains a constant velocity across the damper is proposed as the input to use in experiments. This triangle wave ensures a constant velocity across the damper in order to accurately evaluate the response time of the MR damper. The response time was defined as the time required to make the transition from the initial state to 63.2% of the final state, or one time constant. The time constant is a measure of how long it takes a system to respond to a given input. In other words, the response time is the time necessary for the damper to achieve the desired force upon activation. To demonstrate the method, the response time was found for an MR damper particularly designed and fabricated for vehicle applications. Two cases were considered: activation response time of the damper and deactivation response time of the damper. Both cases were studied during the rebound stroke of the damper. It was found that the response time of the MR damper under activation and deactivation was 15.4 ms and 13.9 ms respectively. The results are comparable to those found in the literature.

scholarly journals Parametric identification of the mathematical model of the functioning of tribosystems in the conditions of boundary lubrication

2021 ◽  
Vol 101 (3) ◽  
pp. 6-14
Author(s):  
A. Voitov ◽  
Keyword(s):  
Quality Factor ◽  
Time Constant ◽  
Boundary Lubrication ◽  
Rapid Change ◽  
Parametric Identification ◽  
Surface Layers ◽  
Sliding Speed ◽  
External Conditions ◽  
Time Required ◽  
Friction Surfaces

The parametric identification of the tribosystem as an object of modeling the functioning of tribosystems in the conditions of boundary lubrication is performed in the work. Using the analysis of the dimensions of significant factors, expressions are obtained to calculate the gain and time constants. It is established that the coefficient takes into account the degree of influence of the load, sliding speed, tribological characteristics of the lubricating medium on the quality factor of the tribosystem. It is shown that the increase in the coefficient will have a positive effect on the processes inherent in tribosystems during operation. Coefficient – characterizes the magnitude of the change in volumetric wear rate and friction coefficient when changing the magnitude of the load, sliding speed, quality factor of the tribosystem. Coefficient – characterizes the ability of the tribosystem to self-organize when changing the values of the input parameters by rearranging the surface layers of materials from which the triboelements are made during secondary running-in. It is shown that the value of the coefficient is large will contribute to the rapid change in the roughness of the friction surfaces, the restructuring of the structure of the surface layers, the appearance of oxidizing films on the friction surfaces (secondary structures). It is proved that the time constant – this is the time required to change the roughness of the friction surfaces and rearrange the structure of the materials of the surface layers when changing external conditions. Time constant characterizes the time during which there is a stabilization of the temperature gradient by volume of triboelements, taking into account the thermal conductivity of materials when changing external conditions. Time constant characterizes the time during which the tribosystem returns to a steady state of operation after the cessation of the outrageous force, or the time to stabilize the parameters in the new mode of operation. It is proved that the value will be optimal for the process of self-organization. It is shown that one of the factors that can control the value , this is the sliding speed

Annealing of Irreversible Defects in Hydrogenated and Unhydrogenated Amorphous Silicon Thin Films

1990 ◽  
Vol 192 ◽  
Author(s):  
G. N. Parsons ◽  
C. Wang ◽  
G. Lucovsky
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Substrate Temperature ◽  
Amorphous Silicon ◽  
Time Constant ◽  
Annealing Time ◽  
Atomic Hydrogen ◽  
Characteristic Time ◽  
Silicon Thin Films ◽  
Anneal Time

ABSTRACTWe have prepared unhydrogenated and hydrogenated ([H] = 14 at.%) amorphous silicon thin films using magnetron sputtering with substrate temperature, TS = 40°C. After deposition, the films were annealed at temperatures between 150 and 200°C and conductivity was measured as a function of anneal time. We find that for that for both materials, the conductivity changes non-exponentially with annealing time. The characteristic time constant for annealing at 175°C is approximately the same in unhydrogenated films (τ≈100min) as found in films containing 14 atomic % hydrogen (τ≈200min).

Continuous Optimal Infeed Control for Cylindrical Plunge Grinding, Part 2: Controller Design and Implementation

2004 ◽  
Vol 126 (2) ◽  
pp. 334-340 ◽  
Author(s):  
Shaoqiang Dong ◽  
Kourosh Danai ◽  
Stephen Malkin
Keyword(s):  
Control System ◽  
Controller Design ◽  
Control Policy ◽  
Noise Robustness ◽  
Practical Implementation ◽  
Wheel Wear ◽  
Plunge Grinding ◽  
Cylindrical Grinding ◽  
Safety Margins ◽  
On Line

This is the second of two papers concerned with on-line optimization of cylindrical plunge grinding cycles with continuously varying infeed control. In the first paper [1], dynamic programming was applied to a simulation of the cylindrical grinding process in order to explore the characteristics of optimal grinding cycles. Optimal cycles were found to consist of distinct segments each with predominant constraints. An optimal control policy was formulated with the infeed rate within each segment determined according to the prevailing constraint. The present paper is concerned with the design of the controller and its implementation. The control system to implement the optimization policy is described together with provisions to enhance robustness to modeling uncertainty and measurement noise. Robustness provisions include model adaptation by parameter estimation from on-line measurements of size and power, and incorporation of safety margins in the optimization process. Problems associated with practical implementation of the control system, stemming from power limitations and wheel wear, are also discussed. The controller performance is demonstrated on an instrumented internal cylindrical grinding machine.

Transient Capacitance Studies of a Low-Lying Electron Trap in n-type Silicon

1980 ◽  
Vol 2 ◽  
Author(s):  
G. E. Jellison ◽  
J. W. Cleland ◽  
R. T. Young
Keyword(s):  
Electric Field ◽  
Time Constant ◽  
Pulse Width ◽  
Characteristic Time ◽  
Depletion Region ◽  
Electron Trap ◽  
Majority Carrier ◽  
Type Silicon ◽  
Transient Capacitance ◽  
Capacitance Response

ABSTRACTA new electron trap has been observed in electronirradiated n-type silicon at Ec − ET = 0.105 eV using transient capacitance techniques. It is found that the maximum transient capacitance response is observed only when the majority carrier pulse width is much smaller than some characteristic time constant, and when the time between pulses is much larger than another characteristic time constant. It is shown that this defect is related to an electron trap at Ec−ET = 0.172 eV (probably the oxygenvacancy or A-center); it is believed that this trap is induced by the electric field found in the depletion region of a p-n junction.

scholarly journals Design for Assembly Line Performance: The Link Between DFA Metrics and Assembly Line Performance Metrics

2010 ◽  
Author(s):  
Marcos Esterman ◽  
Krishna Kamath
Keyword(s):  
Cycle Time ◽  
Assembly Line ◽  
Performance Metrics ◽  
Precedence Constraints ◽  
Design Tool ◽  
Design Stage ◽  
Design For Assembly ◽  
Minimum Number ◽  
Time Required ◽  
The Impact

While Design for Assembly (DFA) has been a useful design tool, it is not explicitly linked to actual manufacturing line performance. The motivation for this research came from the desire to link DFA directly to line balance and cycle time performance. The natural question that arose was whether these issues could be considered at the design stage by using the metrics that are derived from a DFA analysis. It is known that the time required to assemble a product can be estimated from both a DFA analysis and from a manufacturing analysis. This work links these two analysis methods so that the manufacturing parameters can be estimated and used to guide the design of a product. Starting with a DFA analysis, the minimum number of workstations needed to balance the line that will maintain the production rate (takt time) and precedence constraints is determined. Then the precedence constraints are systematically relaxed in order to generate measures on a component-by-component basis as to the impact it could have on reducing cycle time and improving line balancing performance. These measures, coupled with an understanding of precedence types, are used to identify design improvements to a product. To illustrate how product designer can consider assembly line performance issues during the design stage of the product, the methodology has been applied to an ABS brake assembly.

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