Cam Mechanism Research Articles

THE EFFICIENCY OF USING CAM MECHANISMS TO OPERATE THE EQUIPMENT FOR OPENING AND INTERRUPTING WATERING FURROWS

Due to climate change, there have been changes in temperature, distribution and precipitation, phenomena that have led to the development of technologies that increase the efficiency of precipitation water use and support the preservation of soil quality. The paper presents some theoretical considerations on the cam mechanisms for actuating the working parts the equipment for opening and interrupting watering furrows are provided with; setting the optimal dimensions of the blades of the equipment for furrow opening through the experiments performed is also made. By using the cam mechanisms in the equipment for opening and interrupting watering furrows both superior quality indices in the execution of the work but also a quiet operation of the equipment are obtained and by optimizing the size of the working part, the volume of water accumulated between furrows increases significantly.

Investigation of effects of surface roughness on the performance of cam mechanisms

The surface roughness of two contacting surfaces significantly influences the tribological performance of the mechanical elements. Their impression is more pronounced under the mixed elasto-hydrodynamic lubrication condition. The cam and flat follower mechanism is a typical sample in which adverse tribological conditions, including direct boundary interactions occurs. In this study, effects of surface roughness on the friction force and friction coefficient are investigated using engine oil at different test conditions in a cam follower mechanism. It is seen that decreasing roughness of the contact surfaces has a more desirable tribological performance, and decrease friction coefficient, therefore increase wear resistance.

Investigation of effects of boron additives on performance of cam mechanisms

The use of additives in the contacting surfaces is essential for the formation of a thin lubricant film, which separates the moving surfaces from each other. Boron compounds, in particular, are very helpful for the sliding surfaces. The aim of the investigation is to clarify how the boron additives influence the lubricating ability of the engine oil using in the sliding contact of the cam-follower. In this study, the considerable results in the tests of engine oil with boron compounds and with base oil are obtained. And also, the influences of the minimize interface friction has been observed under different test conditions.

Study of the Jumping Phenomenon in a Cam and Follower Mechanism

Study of the Jumping Phenomenon in a Cam and Follower Mechanism

An integrally formed design for the rotational balancing of disk cams

In this paper, an improved and generic design of counterweights that can be applied to achieve complete rotational balance of disk cams is proposed. A pair of integrally formed counterweight bumps is added to a disk cam with an arc-slot hole in order to achieve static and dynamic balancing conditions simultaneously. The radially outside contour of each counterweight bump is exactly part of the cam profile. With the aid of analytical expressions and derived geometric properties for the cam profile, a systematic approach for obtaining the theoretical solutions of the integrally formed counterweights is established based on derivations of balancing conditions and a solution procedure. An optimization model is also established. Subsequently, to verify the feasibility and effectiveness of the proposed design, two hardware models were designed and built for measuring their induced vibrations and shaking forces. Experimental results revealed that the counterweighted disk cam could suppress the induced vibrations and reduce the induced shaking forces, and especially could effectively suppress the intensity of the resonance phenomena. Hence, the proposed design can improve the dynamic performance of disk cam mechanisms.

Design and optimisation of load-adaptive actuator with variable stiffness for compact ankle exoskeleton

To overcome the limitations of linear series elastic actuators (SEAs) with constant stiffness, a novel load-adaptive actuator with variable stiffness is proposed for actuating ankle exoskeletons through an inverted slider-crank mechanism. Using the proposed actuator, the stiffness of the exoskeleton can be adjusted passively based on the external load and joint angle. To achieve compactness, a novel nonlinear spring mechanism with user-defined load–deflection behaviour is designed by combining a cam mechanism with parabolic beams; this proposed mechanism is used as the series elastic element of the proposed actuator. Dimensional optimisation of the ankle exoskeleton, including the actuator, is subsequently performed for maximising the energy efficiency based on gait biomechanics and considering the constraints of the inverted slider-crank mechanism, electric motor, and the nonlinear spring mechanism. Simulation and experimental results show that the energy efficiency is improved by using the proposed load-adaptive actuator-powered ankle exoskeleton compared with using an exoskeleton driven by linear SEAs.

Electronic system of rubber belt electro-mechanical continuously variable transmission for motorcycle applications

This paper deals with the design of electronic system for changing the transmission ratio of a rubber belt electro-mechanical continuously variable transmission (CVT) for motorcycle applications. In this CVT, the rubber belt is used as a medium to transfer both the speed and torque from the input pulley to the output pulley based on contact friction force existed between the belt and both pulley surfaces. Each pulley set consists of one fixed and one sliding pulley sheaves. The axial position of the input sliding pulley sheave is detected using a two channel incremental rotary encoder and controlled by an electro-mechanical shifter system utilizing DC motor, actuator gear set and cam mechanism. The sliding sheave of the output pulley is axially pushed by contra spring to provide sufficient belt compression for preventing belt slip. The CVT ratio is changed by varying the input and output belt-pulley contact radii. It can be done by controlling the axial position of sliding input pulley sheave, the angular speeds of input and output pulleys are sensed using one channel incremental rotary encoders. By knowing these two speed values, the CVT ratio can be computed. The microcontroller system of Arduino is programmed to detect and control the axial position of the input sliding pulley sheave to regulate the CVT ratio. The experimental results show that the electronic system can perform the CVT ratio changes adequately.

Contact Stress Distribution of a Pear Cam Profile with Roller Follower Mechanism

The problem of this paper is the high contact stress at the point of contact between the cam and the follower. A pear cam and roller follower mechanism were studied and analyzed for different position of the follower and different contact compression load. The objective of this paper is to study the effect of contact compression load on the contact stress distribution of the cam profile at the point of contact. Four different positions of the follower with the cam was considered (0°, 90°, 180°, and 270°). The theory of circular plate was applied to derive the analytic solution of the contact stress. The numerical simulation had been done using ANSYS Ver. 19.2 package to determine the contact stress, while SolidWorks software was used to investigate follower displacement, velocity, and acceleration. Four distinct values of the compression contact load, such as 3.121 N, 6.242 N, 9.364 N, and 12.485 N, were used in the numerical simulation. In the experiment setup, a photo-elastic technique was carried out in the field of polarized light to exhibit the stress distribution on the cam specimen. The annealed PSM-4 backalate material was used in the experiment setup. The experimental value of contact stress was checked and verified analytically and numerically at the point of contact. The innovation in this paper the use of spring-damper system which reduce the value of contact stress at the point of contact. The contact stress was maximum 2.136 MPa when the follower located at 270° with the cam, while the contact stress was minimum 1.802 MPa when the follower located at 180° at compression load 12.485 N.

Analysis of follower motion law and optimization of fitting function in reverse design of cam

Because of its compact structure and reliable performance, the cam mechanism has been widely used in automatic machinery, such as automatic tool changing system, packaging machinery, automatic production line, automatic switching system and so on. At present, a variety of common drive and control devices have been developed with arc cam as the core component. The cam indexing mechanism is a new type of transmission device to realize high speed and high precision intermittent indexing motion. It is widely used and has been studied by more and more scholars at home and abroad, and has achieved remarkable results. At present, its theoretical research has matured. However, because the profile of indexing cam is a non-spiral surface in space, it brings inconvenience to the design and manufacture of cam. When the arc cam is damaged and the design parameters of the original arc cam cannot be known, the original arc cam profile can only be obtained by measuring limited data. In the original parameterized design method, the profile of the arc cam is determined by the motion law of the follower. If the motion law curve of the follower can be obtained, the contour curve of the arc cam can be obtained in reverse. So the problem of solving the profile surface of the cam can be transformed into a follower which meets the requirements the curve of motion law. Taking the CAM Z175 as an example, this paper describes in detail the whole process of motion rule analysis, optimization of the motion law curve and simulation verification in CAM reverse design.

Increasing the Wear Resistance of the Friction Surfaces of Rotating Parts Made of Bearing Steels Through Hardening Processing Methods

During the study, it was found that the basic technological processes of forming cylindrical working surfaces of friction pairs do not fully provide a rational combination of micro geometric characteristics and physical and mechanical properties of the surface layer. Therefore, we proposed to evaluate the wear resistance of the working surfaces of parts to use a complex indicator that takes into account the influence of technological factors on the properties of the material and the performance characteristics of the surface layer for the running-in and continuous operation modes. Plots of distribution of equivalent stresses by indentors of different geometric configurations are constructed and the optimal shape and material of the deforming element are established. A model of the dynamics of the deformation of the workpiece with a single-axis elastic tool has been developed, which can be used to calculate the radial force in the contact zone. The calculation scheme corresponds to the scheme of the axial cam mechanism. Based on the analysis of the influence of the geometric characteristics of the deforming element on the parameters of the deformation process, a barrel-type indenter was developed for fixing which a slider-type holder was developed with the ability to adjust the stiffness of the dynamic system.

Thermomechanical Effects on Electrical Energy Harvested from Laminated Piezoelectric Devices

Piezoelectric materials are used to harvest ambient mechanical energy from the environment and supply electrical energy via their electromechanical coupling property. Amongst many intensive activities of energy harvesting research, little attention has been paid to study the effect of the environmental factors on the performance of energy harvesting from laminated piezoelectric materials, especially when the temperature in the operating condition is different from the room temperature. In this work, thermomechanical effects on the electrical energy harvested from a type of laminated piezoelectric devices, known as thin layer unimorph ferroelectric driver (called THUNDER) were investigated. Three configurations of THUNDER devices were tested in a controlled temperature range of 30–80 °C. The THUNDER devices were pushed by using a cam mechanism in order to generate required displacements and frequencies. The experimental results exhibited a detrimental effect of the elevated temperature on the generated voltage and the harvested electrical power. It is due to changes in residual stress and geometry. These results are advantageous for many applications of the THUNDER devices and for future design of a new laminated piezoelectric sensor and energy harvester in an elevated temperature environment.

Design and Synthesis of Single-Actuator Walking Robots via Coupling of Linkages

This paper deals with the development of single actuator walking robots designed by coupling of two mechanisms. The advantages of such robots are the simplicity of the design and its control system. In this paper, three various design concepts are carried out via coupling of two units which are four-bar linkages, slider-crank mechanisms, and a cam mechanism and a pantograph linkage. The geometrical syntheses of these mechanisms have been analyzed, and based on them, analytical and numerical methods have been adopted to ensure the reproduction of given trajectory similar to the human walking gait. Three single-actuator robots have been designed based on these mechanisms where two of them can be easily reconfigured to reproduce gaits with different lengths or even tilted gaits which make the robot able to climb stairs. All suggested design concepts have been validated through CAD simulations carried out via ADAMS software.

Analysis of impact cam mechanisms from the point of view of the rationality of their use in drilling machines

Modern drilling machines designed for the destruction of rocks have a diverse structure, various performance characteristics and in most cases a well-defined limited scope of application. One of the variants of the design of such machines is the integration of impact cam mechanisms into their structure, the variety of which allows achieving the specified working conditions. The most suitable one for impact machines is the front cam mechanism, in which the rotational movement of the cam is converted into the translational movement of the driven link – the pusher. Only cam mechanisms allow implementing a certain law of motion of the output-working link accurately. This article provides an overview of the well-known patented impact machines equipped with impact cam mechanisms. A brief description of each technical solution is provided, indicating mechanism differences and uniqueness. Based on the results of the critical analysis of the found machines and mechanisms, the tasks of further research are formulated. These results will be the development of scientific knowledge in the field of the use of cam mechanisms in impact machines, namely in drilling machines that can automatically adapt to operating conditions.

An Integrated Piezoelectric Inertial Actuator Controlled by Cam Mechanisms

This paper presents a battery-supplied piezoelectric actuator controlled by cam mechanisms. The actuator moves by matching the phase difference between the clamp and the excitation cams. The piezoelectric bimorphs of the actuator are excited by signals from a contact switch driven by the excitation cam. The crucial parameters of the cam mechanisms, contour curve, stroke, and phase difference of clamp and excitation cams are designed and verified by tests. A series of performance tests (such as frequency, voltage, etc.) are carried out, demonstrating a minimum step displacement of $0.7~\mu \text{m}$ and a minimum repeatability parameter of $0.18~\mu \text{m}$ . The performance of the actuator with the battery supply is basically consistent with the DC power. The proposed actuator can be powered by the battery and operates stably, which provides a new idea for the integration of piezoelectric actuators.

Design of “S” type track carbon free car based on cam mechanism

Reverse part model based on motion trajectory is a common method in mechanism design. Compared with the traditional calculation method, it is simple and practical, and can simulate the reconstruction of the trajectory. In this paper, S-type carbon-free car was taken as an example. Firstly, the motion trajectory of the ideal car path was given. UG software was used to obtain the curve characteristics, established a mathematical model, and took the curve into the model to obtain the data of cam coordinate points. Then the MATLAB software was used to draw the cam contour and analyzed the feasibility of cam operation. The vehicle trajectory simulation was realized in MATLAB environment. Finally, the reasonable cam contour coordinate point data was imported into UG software to establish a 3D model of the cam, and the car track was repeatedly optimized to get the optimal cam shape. The rationality and the accuracy of the model were verified by the carbon-free car made by the scheme, and the corresponding guidance was provided for the research of others.

Application and research on digital twin in electronic cam servo motion control system

With the development and extensive applications of big data and artificial intelligence (AI), the manufacturing industry is gradually becoming increasingly intelligent. In the industrial sector, digital twin can greatly promote the innovation of products in the processes of design, production, operation, and maintenance. The traditional cam mechanism in mechanical reciprocating motion is constrained by the profile curve and lacks flexibility, which will be replaced by a new, flexible and controllable electronic cam. This paper designs a digital cam servo motion system based on digital twin. Using the multi-dimensional simulation software and taking advantage of virtual-real interaction ability of digital twin technology, the trajectory planning, state monitoring, and precise control of the electronic cam motion can be realized. The results show that the electronic cam servo motion control driven by digital twins has good observability, robustness, and adaptability. The scheme is feasible and practical, and provides reference for the design, manufacture, and application of electronic cam using digital twin technology.

Analysis of assembly defects in the cam curved groove mechanism

PurposeThis paper aims to propose an elementary approach toward the identification of assembly defects of a cam curved groove mechanism.Design/methodology/approachA numerical analysis method for identifying the assembly defects of the cam curved groove mechanism is proposed by resorting to Hertz contact theory. A general mathematical model is established to analyze the kinematic and dynamic characteristics with an interference fit between the main roller and cam curved groove, including the contact points of the external and internal ring.FindingsThe analysis method of the contact point characteristics of the cam curved groove mechanism is given in this paper, and the kinematic and dynamic characteristics of the main roller can be analyzed. The numerical examples presented in this paper are implemented in MATLAB, feasibility and validity of the above algorithm are verified by the finite element method.Originality/valueRegarding the defects of the interference fit, the findings of this paper can serve as a reference for researchers in reducing the defects in the design process of the cam mechanism.

Analysis of Cam and Follower Mechanism to Reduce Jerk and Induced Stresses

The objective of this work is to model, design and analyse a cam and follower mechanism, which has minimum jerk and induced stresses for a defined motion. A cam and follower mechanism of a vehicle was chosen for analysis and suitably modified so as to minimize the jerk and stresses induced in the cam and also follower. The expressions for displacement, velocity and acceleration are derived by adopting a geometrical procedure. The kinematic analysis is further extended to dynamic analysis. Based on the results of kinematic and dynamic analysis, it was decided to modify the cam profile in order to reduce the jerk, an unwanted phenomenon that occurs due to sudden change of acceleration. Different cam profiles were generated by varying the nose radius and central distance between the base circle and the nose circle, maintaining the lift of the follower and base circle diameter constant. The work was further extended to determine the stresses developed in both the cam and follower. This was carried out using SOLIDWORKS and ANSYS Workbench. A comparative study is made with reference to the stresses and jerk to arrive at the best cam and follower design.

The conjugate profile of the circular teeth of a spur gear. Part I: Problem statement

The paper presents the manner of finding the conjugate profile of a circular tooth of a spur gear. A synthesis of the method of enveloping applied to the cam mechanisms is presented in order to relate it the profile of the spur gears. The main argument of employing cam mechanisms is the possibility of obtaining any follower law of motion using a minimum number of parts- the cam and the follower. In the case of the mechanisms with flat face follower, the cam is obtained as an envelope of successive positions of the follower. The gear mechanisms are a particular case of cam mechanisms. The major requirement imposed to this mechanism is to transmit the rotational motion between two shafts with a constant transmission ratio. From here it results that the profile a geared wheel can be completely identified when there are known the distance between the axes, the transmission ratio and the profile of one of the wheels. The most used curve as tooth flank is the involute of a circle, due to the fact that this curve has as conjugate curve an involute, too. Although the involute profiles are common in most of the technical appliances, there are cases when they cannot satisfy the functional constraints of certain devices. As example, in the mechanical watches technology, large transmission ratios are needed and the gears with small number of teeth are used as routine. But this necessity is better fulfilled by cycloidal profiles than the involute ones. The circular profiles for the spur gear are the oldest gears due to the simple profile. The exact conjugate profile of a circular tooth obtained by enveloping by means of dedicated software is presented.

The optimization design and test of camfull-row-pick-up seeding mechanism

The mechanism components and working principle were analysed, and then cam mechanism was simplified into slider-crank mechanism to facilitate the establishment of kinematic model. The target optimization function for structural parameters was solved out via mathematical model combined with the transplanting requirements, then a computer-aided analysis program based on Visual Basic 6.0 was developed for optimizing structural parameters of the mechanism. According to the optimized structural parameters, the three-dimensional model of mechanism was established and the automatic seedling pick-up test-bed was conducted. The analysis of kinematic simulation and the test of prototype test were carried out. The success rate of picking up seedlings reaches 95% and efficiency of taking seedling is 3600 strains per hour. The cam full-row-pick-up seedling mechanism is feasible and effective to achieve the operation requirements of whole-row-pick-up seedling.