A Versatile Acceleration-Based Cam Profile for Single-Dwell Applications Requiring Cam-Follower Clearance During Dwell

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Forrest W. Flocker
Keyword(s):  
Closed Form ◽  
Velocity Function ◽  
Manufacturing Operations ◽  
Equation Solving ◽  
Cam Follower ◽  
Cam Profile

Presented in this paper is an asymmetric acceleration-derived cam motion program suitable for single-dwell cam-follower systems with clearance between the cam and follower during dwell. Asymmetric rise and fall is included as this is desirable in certain manufacturing operations and machines that require a quick rise or fall. The motion program for the cam-follower actuation is derived from the follower acceleration so that designers can control the ratio of the magnitudes of positive and negative accelerations. This provides cam designers more control over the cam-follower interface force and therefore more control over factors such as cam wear and the potentially destructive phenomenon known as “follower jump.” The motion program used to close and open the clearance gap is derived from a velocity function, allowing more control of follower inertia during the important clearance closing event. The motion program is presented in closed-form, suitable for implementation in standard engineering equation-solving software.

A Versatile Acceleration-Based Cam Profile for Single-Dwell Applications Requiring Cam-Follower Clearance During Dwell

2011 ◽  
Author(s):  
Forrest W. Flocker
Keyword(s):  
High Speed ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Velocity Function ◽  
Gas Leakage ◽  
Poppet Valve ◽  
Equation Solving ◽  
Cam Follower ◽  
Cam Profile

Presented in this paper is a cam motion program suitable for single-dwell cam-follower systems with built-in clearance between the cam and follower during the dwell portion of the cycle. This makes the motion program particularly well-suited to applications such as valve trains in internal combustion engines in which cam-follower clearance is necessary to ensure proper seating of a poppet valve, preventing gas leakage across the seal. The motion program for the cam follower is derived from the follower acceleration function so that designers can control the ratio of the magnitudes of positive and negative accelerations. This provides cam designers more control over the cam-follower interface force and therefore more control over factors such as cam wear and the potentially destructive phenomenon known as “follower jump.” Included in the motion program is asymmetric rise and fall that allows different times for these events. The follower acceleration is designed to be smooth enough to provide continuous jerk throughout the actuation phase, thereby tending to reduce undesirable residual vibrations. The motion program used to close and open the clearance gap is derived from a velocity function, allowing more control of follower inertia during the important clearance closing event. The motion program is presented in a form appropriate for implementation in standard engineering equation-solving software, giving the cam designer easy control over important parameters in high-speed cam-follower systems.

A Versatile Cam Profile for Controlling Interface Force in Multiple-Dwell Cam-Follower Systems

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Forrest W. Flocker
Keyword(s):  
Closed Form ◽  
High Speed ◽  
Maximum Magnitude ◽  
Design Objective ◽  
Standard Equation ◽  
Negative Acceleration ◽  
Cam Follower ◽  
Cam Profile ◽  
Harmonic Analyses ◽  
Spreadsheet Software

Cam follower systems are widely used in manufacturing because of their precise motion and ability to easily dwell. The cam typically drives a follower in some precise motion needed to accomplish a manufacturing task. Presented in this paper is a closed-form modified trapezoidal cam motion function with adjustable positive and negative acceleration. The profile is suitable for multiple-dwell cam and follower applications. The profile is particularly applicable to high-speed cams in which the follower acceleration is a primary design objective. The main benefit of the profile is that it allows cam designers to easily set limits on the positive and negative acceleration to achieve design objectives. Additional benefits are that the cycle jerk is continuous and that the cam designer can control the maximum magnitude of jerk. The motion program is presented in closed-form for easy implementation in standard equation-solver or spreadsheet software. Dynamic and harmonic analyses are presented to illustrate the benefits of the profile.

Influence of Varying Cam Profile and Follower Motion Event Types on Parametric Vibration and Stability of Flexible Cam-Follower Systems

1994 ◽  
Vol 116 (1) ◽  
pp. 298-305 ◽  
Author(s):  
A. I. Mahyuddin ◽  
A. Midha
Keyword(s):  
Closed Form ◽  
Numerical Algorithm ◽  
Parametric Instability ◽  
Excitation Amplitude ◽  
Companion Paper ◽  
Valve Train ◽  
Positional Error ◽  
Parametric Stability ◽  
Cam Follower ◽  
Cam Profile

A method to study parametric stability of flexible cam-follower systems, based on Floquet theory, as well as a closed-form numerical algorithm to compute periodic response of the system, have been developed in a companion paper. These are applied to an automotive valve train, modeled as a single-degree-of-freedom vibration system. The inclusion of the transverse and rotational flexibilities of the camshaft results in a system that is governed by a linear, second-order, ordinary differential equation with time-dependent coefficients. In this paper, the parametric stability of the system is studied, and the results are presented in the form of parametric stability charts. The regions of instability are plotted on the nondimensionalized frequency and excitation (amplitude) parameter plane. The maximum positional error of the follower motion, analyzed by the closed-form numerical algorithm, enables a novel presentation of three-dimensional stability and response charts. Stability of the system is investigated for three types of follower motion events and four different cam profiles. The effect of damping on parametric instability is also studied. A comparative study of these event and cam profile types reveals some very interesting and hitherto unknown results.

Spline Based Design of Cam Contours for Improved Dynamic Performance

1993 ◽  
Author(s):  
Holly K. Ault ◽  
James C. Wilkinson
Keyword(s):  
Dynamic Performance ◽  
Integrated Design ◽  
Polynomial Functions ◽  
Piecewise Polynomial ◽  
Cam Design ◽  
Piecewise Polynomial Functions ◽  
Cam Follower ◽  
Cam Profile ◽  
Pitch Curve ◽  
Design And Manufacture

Abstract A method for the integrated design and manufacture of radial plate cams is discussed. Currently, a cam-follower system is designed by specifying constraints on the motion of the follower. The physical cam contour or cam pitch curve are not mathematically defined. The cam is manufactured from the discretized follower motion program. A new method for cam design is proposed which will produce a smooth, mathematically defined cam pitch curve while maintaining the proper constraints on the follower motion. Piecewise polynomial functions in the form of rational and/or non-rational splines may be used. Cams will be manufactured using smoothed profiles and tested for improved dynamic performance. The results of initial investigations of cam profile design for this research are presented.

Valve Gear Refinement

2000 ◽  
Vol 124 (1) ◽  
pp. 86-90 ◽  
Author(s):  
Jurij Avsec ◽  
Milan Marcic ◽  
Maks Oblak
Keyword(s):  
Mathematical Model ◽  
Cam Design ◽  
Cam Follower ◽  
New Type ◽  
Cam Profile ◽  
Profile Design ◽  
Comparison Of The Results ◽  
The Mathematical Model ◽  
Valve Gear ◽  
Lubrication Properties

This paper describes a new type of valve gear cam—MULTICAM—which consists of seven curves and allows an optimum cam profile design. In order to calculate the cinematic and dynamic values and to assess the minimum oil film thickness in the valve gear, the mathematical model of an ideal valve gear was used. In addition, the comparison of the results between the polysine cam and the new MULTICAM cam design was made. By means of the new cam design the Hertz pressures were reduced at the point of contact between the cam and the cam follower and the lubrication properties at the top of the cam improved.

Synthesis of cam profile using classical splines and the effect of knot locations on the acceleration, jump, and interface force of cam follower system

2011 ◽  
Vol 225 (12) ◽  
pp. 3019-3030 ◽  
Author(s):  
U Chavan ◽  
S Joshi
Keyword(s):  
Displacement Function ◽  
Physical Parameters ◽  
Spline Curves ◽  
Design Variables ◽  
Negative Acceleration ◽  
Positive Acceleration ◽  
Large Jump ◽  
Cam Follower ◽  
Displacement Profile ◽  
Cam Profile

Large positive acceleration against a load creates cam follower interface force that can cause excessive wear. Negative acceleration tends to reduce the cam follower interface force, and if the negative acceleration is sufficiently large, jump between the cam and follower can occur. Hence, these are the two main concerns of cam designers. This study presents a new approach to adjust the acceleration, interface force, and jump in the early phase of cam design. Knot locations of polynomial pieces of spline curves are considered as design variables which gives variety of cam profiles. Here, design process starts from displacement profile and there is no need for predefined acceleration curves. A single dwell cam displacement function is defined by classical spline curve, made up of four polynomial pieces that are tied together at their ends, called knots. Specifications of these knots are considered for synthesis and analysis of cam follower system. Mathematical relation between interface force and knot locations is presented as wear and jump models. These models are useful to reduce wear and jump by proper placement of the knots on the basis of interface force. By dynamic simulation of cam follower system, cam curves are drawn for different cases of knot locations and good resemblance was found with theoretical curves. This study suggests the cam designers have the added option to control the kinematic and dynamic quantities without changing the physical parameters of cam follower system.

scholarly journals Cam Mechanisms Reverse Engineering Based on Evolutionary Algorithms

Electronics ◽  
2021 ◽  
Vol 10 (24) ◽  
pp. 3073
Author(s):  
Monica Tiboni ◽  
Cinzia Amici ◽  
Roberto Bussola
Keyword(s):  
Genetic Algorithm ◽  
Reverse Engineering ◽  
Dynamic Time Warping ◽  
Automated Manufacturing ◽  
Time Warping ◽  
Planning Techniques ◽  
Innovative Method ◽  
Cam Follower ◽  
Cam Profile ◽  
Dynamic Time

Cam follower mechanisms are widely used in automated manufacturing machinery to transform a rotary stationary motion into a more general required movement. Reverse engineering of cams has been studied, and some solutions based on different approaches have been identified in the literature. This article proposes an innovative method based on the use of an evolutionary algorithm for the identification of a law of motion that allows for approximating in the best way the motion or the sampled profile on the physical device. Starting from the acquired data, through a genetic algorithm, a representation of the movement (and therefore of the cam profile) is identified based on a type of motion law traditionally used for this purpose, i.e., the modified trapezoidal (better known as modified seven segments). With this method it is possible to estimate the coefficients of the parametric motion law, thus allowing the designer to further manipulate them according to the usual motion planning techniques. In a first phase, a study of the method based on simulations is carried out, considering sets of simulated experimental measures, obtained starting from different laws of motion, and verifying whether the developed genetic algorithm allows for identifying the original law or approximating one. For the computation of the objective function, the Euclidean norm and the Dynamic Time Warping (DTW) algorithm are compared. The performed analysis establishes in which situations each of them is more appropriate. Implementation of the method on experimental data validates its effectiveness.

The Design of Disk Cam Mechanisms With a Translating Follower Having an Added Dual-Roller Intermediate Link

2020 ◽  
Author(s):  
Kuan-Lun Hsu ◽  
Sun-Liang Chou
Keyword(s):  
Contact Stress ◽  
Normal Force ◽  
Design Procedures ◽  
Cam Mechanism ◽  
Working Cycle ◽  
Cam Follower ◽  
Cam Profile

Abstract This paper provides a methodology to design a disk cam mechanism that has a translating follower with dual rollers. Dual rollers are joined by an oscillating link and can contact cam profile simultaneously throughout working cycle of cam rotation. The application of this novel follower can offer two engagements in cam-follower pair to spread the induced normal force and reduce the contact stress between cam and follower. Two examples are worked to demonstrate application of design procedures and to illustrate the capability of reducing contact stress of this novel follower. The results show that the contact stress of such a cam mechanism can be reduced by 28.85% in comparison with that of the cam mechanism with a common translating roller follower.

Cam profile optimization for the delivery system of an offset press

2016 ◽  
Vol 231 (23) ◽  
pp. 4287-4297 ◽  
Author(s):  
Tiancheng Ouyang ◽  
Pan Wang ◽  
Haozhong Huang
Keyword(s):  
Dynamic Simulation ◽  
Delivery System ◽  
Dynamic Characteristics ◽  
Optimization Procedure ◽  
Optimization Method ◽  
Adams Software ◽  
Cam Follower ◽  
Cam Profile ◽  
Profile Optimization ◽  
Single Objective

In this paper, a relatively new strategy known as unified optimization is applied to the cam profile optimization for the delivery system of an offset press by integrating the procedure of single objective optimization with ADAMS software. The proposed approach mainly consists of two parts that includes a single objective optimization procedure and a multibody dynamic model of cam–follower mechanism. For the procedure of single objective optimization, the design process starts from defining the follower acceleration profile by using a modified trapezoidal curve, then genetic algorithm is adopted to determine the evaluating indexes for the kinematic behavior of cam–follower mechanism in multiobjective optimization. Subsequently, sequential quadratic programming, which deals well with equality and inequality constrains, is selected as single objective optimized algorithm in this part. On the other hand, the dynamic simulation developed by ADAMS software is carried out to investigate the dynamic characteristics of cam–follower mechanism. Finally, an optimization cycle, also known as iterative process, is proposed to implement the procedure of single objective optimization and dynamic simulation alternately to improve the kinematic and dynamic characteristics of cam–follower mechanism fully. The cam profile optimization method presented in this paper provides a new tool for cam designers to avoid the undesirable impact and follower jump.

Addressing Cam Wear and Follower Jump in Single-Dwell Cam-Follower Systems With an Adjustable Modified Trapezoidal Acceleration Cam Profile

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Forrest W. Flocker
Keyword(s):  
Additional Benefit ◽  
Factors Affecting ◽  
Large Separation ◽  
A Value ◽  
Cam Follower ◽  
Cam Profile ◽  
Interface Forces

Presented is a modified trapezoidal cam profile with an adjustable forward and backward acceleration. The profile is suitable for single-dwell cam and follower applications. The main benefit of the profile is that it allows cam designers to choose easily a value for the maximum forward or maximum backward acceleration to achieve design objectives. An additional benefit of the profile is that it has a continuous jerk curve. Follower acceleration is one of the primary factors affecting cam wear and follower jump, two main concerns of cam designers. Large forward acceleration against a load creates cam-follower interface forces that can cause excessive wear. Backward acceleration tends to reduce the cam-follower interface force, and if the backward acceleration is sufficiently large, separation between the cam and follower (“follower jump”) can occur. The cam profile presented in this paper gives cam designers an easy way to adjust the maximum forward or backward acceleration to prevent these problems.

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