Synthesis of Inertially Compensated Variable-Speed Cams

2003 ◽  
Vol 125 (3) ◽  
pp. 593-601 ◽  
Author(s):  
B. Demeulenaere ◽  
J. De Schutter
Keyword(s):  
High Speed ◽  
Design Procedure ◽  
Variable Speed ◽  
Speed Variation ◽  
Design Choice ◽  
Cam Follower ◽  
Speed Fluctuation ◽  
Novel Design

Traditionally, cam-follower systems are designed by assuming a constant camshaft speed. Nevertheless, all cam-follower systems, especially high-speed systems, exhibit some camshaft speed fluctuation (despite the presence of a flywheel) which causes the follower motions to be inaccurate. This paper therefore proposes a novel design procedure that explicitly takes into account the camshaft speed variation. The design procedure assumes that (i) the cam-follower system is conservative and (ii) all forces are inertial. The design procedure is based on a single design choice, i.e., the amount of camshaft speed variation, and yields (i) cams that compensate for the inertial dynamics for any period of motion and (ii) a camshaft flywheel whose (small) inertia is independent of the period of motion. A design example shows that the cams designed in this way offer the following advantages, even for non-conservative, non-purely inertial cam-follower systems: (i) more accurate camshaft motion despite a smaller flywheel, (ii) lower motor torques, (iii) more accurate follower motions, with fewer undesired harmonics, and (iv) a camshaft motion spectrum that is easily and robustly predictable.

Steady-State Rigid-Body Dynamic Response of Cam-Follower Mechanisms

1994 ◽  
Author(s):  
Andi I. Mahyuddin ◽  
Ashok Midha
Keyword(s):  
Steady State ◽  
Dynamic Response ◽  
Rigid Body ◽  
Angular Speed ◽  
Integration Scheme ◽  
Rigid Body Dynamic ◽  
Speed Variation ◽  
Cam Follower ◽  
Speed Fluctuation ◽  
Body Dynamic

Abstract The camshaft of a cam-follower mechanism experiences a position-dependent moment due to the force exerted on the cam by the follower, causing the angular speed of the camshaft to fluctuate. In this work, a method to expediently predict the camshaft speed fluctuation is developed. The governing equation of motion is derived assuming that the cam-follower system is an ideal one wherein all members are treated as rigid. An existing closed-form numerical algorithm is used to obtain the steady-state rigid-body dynamic response of a machine system. The solution considers a velocity-dependent moment; specifically, a resisting moment is modeled as a velocity-squared damping. The effects of flywheel size and resisting moment on camshaft speed fluctuation are studied. The results compare favorably with those obtained from transient response using a direct integration scheme. The analytical result also shows excellent agreement with the camshaft speed variation of an experimental cam-follower mechanism. The steady-state rigid-body dynamic response obtained herein also serves as a first approximation to the input camshaft speed variation in the dynamic analysis of flexible cam-follower mechanisms in a subsequent research.

Designing Dynamically Compensated and Robust Cam Profiles With Bernstein-Bézier Harmonic Curves

1997 ◽  
Author(s):  
Lakshmi N. Srinivasan ◽  
Q. Jeffrey Ge
Keyword(s):  
High Speed ◽  
Design Procedure ◽  
Vibration Characteristics ◽  
Resonant Vibrations ◽  
Residual Vibration ◽  
Numerical Examples ◽  
Polynomial Curves ◽  
Harmonic Content ◽  
Cam Follower ◽  
Design Speed

Abstract This paper deals with the problem of designing dynamically compensated cam profiles to minimize residual vibrations in high-speed cam-follower systems. The traditional Polydyne method is modified and extended to achieve significant improvement in residual vibration characteristics. First, cam displacement curves are represented by Bernstein-Bézier harmonic curves as opposed to polynomial curves. These recently developed harmonic curves are low in harmonic content and therefore the resulting cam profiles are less prone to induce resonant vibrations in the follower system. Second, the design procedure is expanded such that the residual vibrations of the resulting cam-follower system is not only extinguished at the design speed but also made insensitive to speed variations. Numerical examples are given in the end.

Designing Dynamically Compensated and Robust Cam Profiles With Bernstein-Be´zier Harmonic Curves

1998 ◽  
Vol 120 (1) ◽  
pp. 40-45 ◽  
Author(s):  
L. N. Srinivasan ◽  
Q. Jeffrey Ge
Keyword(s):  
High Speed ◽  
Design Procedure ◽  
Vibration Characteristics ◽  
Resonant Vibrations ◽  
Residual Vibration ◽  
Numerical Examples ◽  
Polynomial Curves ◽  
Harmonic Content ◽  
Cam Follower ◽  
Design Speed

This paper deals with the problem of designing dynamically compensated cam profiles to minimize residual vibrations in high-speed cam-follower systems. The traditional Polydyne method is modified and extended to achieve significant improvement in residual vibration characteristics. First, cam displacement curves are represented by Bernstein-Be´zier harmonic curves as opposed to polynomial curves. These recently developed harmonic curves are low in harmonic content and therefore the resulting cam profiles are less prone to induce resonant vibrations in the follower system. Second, the design procedure is expanded such that the residual vibrations of the resulting cam-follower system is not only extinguished at the design speed but also made insensitive to speed variations. Numerical examples are given in the end.

A Variable-Speed Method for Improving Motion Characteristics of Cam-Follower Systems

1996 ◽  
Vol 118 (2) ◽  
pp. 250-258 ◽  
Author(s):  
Hong-Sen Yan ◽  
Mi-Ching Tsai ◽  
Meng-Hui Hsu
Keyword(s):  
Design Method ◽  
Design Procedure ◽  
Design Criteria ◽  
Displacement Curve ◽  
Variable Speed ◽  
Traditional Design ◽  
Alternative Approach ◽  
Cam Follower ◽  
Motion Characteristics ◽  
Speed Method

A cam is often assumed to be operated at a constant speed in designing a cam-follower system. The motion characteristics of the follower are determined once the cam displacement curve is designed. The traditional design method for improving the motion characteristics is to find a new displacement curve which has better motion characteristics. This paper, however, presents an alternative approach by varying the speed of the cam to reduce the peak values of the follower output motion characteristics. Constraints and design criteria for selecting suitable cam speed trajectories are then developed. Finally, examples are given to illustrate the design procedure and also to show its feasibility.

scholarly journals Part-optimized forming by spatially distributed vaporizing foil actuators

2021 ◽  
Author(s):  
Marlon Hahn ◽  
A. Erman Tekkaya
Keyword(s):  
Process Design ◽  
High Speed ◽  
Specific Impulse ◽  
Design Procedure ◽  
Mathematical Optimization ◽  
Starting Point ◽  
Spatially Distributed ◽  
Lower Tool ◽  
A Minor ◽  
Charging Energy

AbstractElectrically vaporizing foil actuators are employed as an innovative high speed sheet metal forming technology, which has the potential to lower tool costs. To reduce experimental try-outs, a predictive physics-based process design procedure is developed for the first time. It consists of a mathematical optimization utilizing numerical forming simulations followed by analytical computations for the forming-impulse generation through the rapid Joule heating of the foils. The proposed method is demonstrated for an exemplary steel sheet part. The resulting process design provides a part-specific impulse distribution, corresponding parallel actuator geometries, and the pulse generator’s charging energy, so that all process parameters are available before the first experiment. The experimental validation is then performed for the example part. Formed parts indicate that the introduced method yields a good starting point for actual testing, as it only requires adjustments in the form of a minor charging energy augmentation. This was expectable due to the conservative nature of the underlying modeling. The part geometry obtained with the most suitable charging energy is finally compared to the target geometry.

A novel design procedure for tractor clutch fingers by using optimization and response surface methods

2016 ◽  
Vol 30 (6) ◽  
pp. 2615-2625 ◽  
Author(s):  
Oguz Dogan ◽  
Fatih Karpat ◽  
Celalettin Yuce ◽  
Necmettin Kaya ◽  
Nurettin Yavuz ◽  
...  
Keyword(s):  
Response Surface ◽  
Design Procedure ◽  
Response Surface Methods ◽  
Novel Design

The Influence of Variable-Speed Waveforms on Vibration Suppression in Time-Varying Speed Cutting

2013 ◽  
Vol 690-693 ◽  
pp. 2514-2518
Author(s):  
Juan Cong ◽  
Yun Wang ◽  
Wei Na Yu
Keyword(s):  
Wave Speed ◽  
Vibration Suppression ◽  
Sine Wave ◽  
Time Varying ◽  
Variable Speed ◽  
Suppression Effect ◽  
Speed Variation ◽  
Input And Output ◽  
System Input ◽  
Better Than

Through the research on the change of system input and output energy in time-varying speed cutting, the influence of variable-speed waveforms on vibration suppression effect in time-varying speed cutting is quantitatively analyzed in this paper. A conclusion can be drawn that sine wave speed variation is better than triangle wave speed variation in vibration suppression.

Comprehensive design methodology for an engine journal bearing

2000 ◽  
Vol 214 (4) ◽  
pp. 401-412 ◽  
Author(s):  
H Hirani ◽  
K Athre ◽  
S Biswas
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Design Methodology ◽  
Design Procedure ◽  
Maximum Pressure ◽  
Connecting Rod ◽  
Automotive Engine ◽  
Reciprocating Engine ◽  
High Power Output ◽  
Minimum Film Thickness

The trend towards high power output, high speed and low power loss in engines requires a better understanding of bearing behaviour. Research in this area is directed more towards different aspects involved in bearing analyses, rather than providing a comprehensive guideline on design of bearing. This effort compiles the design methodology for selection of diametral clearance and bearing length by limiting the minimum film thickness, maximum pressure and temperature. The design procedure is summarized on the basis of the existing rapid bearing analyses for evaluation of the journal trajectory, minimum film thickness and maximum pressure and simplified thermal analysis. A flow chart is provided for step-by-step bearing design. Finally, two case studies of engine bearings are described: one investigates the VEB bigend connecting-rod bearing for a large industrial reciprocating engine and the other a main crankshaft bearing for an automotive engine. The methodology translates into easy-to-use expressions and the overall procedure is outlined, using practical data to demonstrate how this can be employed effectively by users.

scholarly journals A Novel Design Procedure for Optimal Design of CFS Compression Members

2015 ◽  
Vol V4 (12) ◽  
Author(s):  
Abhishek Raj Sachan ◽  
Ankit Agrawal ◽  
Arpit Kochar ◽  
Keyword(s):  
Optimal Design ◽  
Design Procedure ◽  
Compression Members ◽  
Novel Design

scholarly journals Blade Tip-timing Technology with Multiple Reference Phases for Online Monitoring of High-speed Blades under Variable-speed Operation

2018 ◽  
Vol 18 (6) ◽  
pp. 243-250 ◽  
Author(s):  
Zhang Ji-wang ◽  
Zhang Lai-bin ◽  
Ding Ke-Qin ◽  
Duan Li-xiang
Keyword(s):  
High Speed ◽  
Online Monitoring ◽  
Rotation Speed ◽  
Experimental Tests ◽  
Reference Points ◽  
Variable Speed ◽  
Rotating Shaft ◽  
Virtual Reference ◽  
Blade Tip ◽  
Multiple Reference

Abstract High-speed blades form core mechanical components in turbomachines. Research concerning online monitoring of operating states of such blades has drawn increased attention in recent years. To this end, various methods have been devised, of which, the blade tip-timing (BTT) technique is considered the most promising. However, the traditional BTT method is only suitable for constant-speed operations. But in practice, the rotational speed of turbomachine blades is constantly changing under the influence of external factors, which lead to unacceptable errors in measurement. To tackle this problem, a new BTT method based on multi-phases is proposed. A plurality of phases was arranged as evenly as possible on the rotating shaft to determine the rotation speed. Meanwhile, the corresponding virtual reference point was determined in accordance with the number of blades between consecutive phases. Based on these reference points, equations to measure displacement due to blade vibrations were deduced. Finally, mathematical modeling, numerical simulation and experimental tests were performed to verify the validity of the proposed method. Results demonstrate that the error in measurement induced when using the proposed method is less than 1.8 %, which is much lower compared to traditional methods utilized under variable-speed operation.

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