Disc Cam Mechanisms Research Articles

Innovative Designs for Cotton Bionic Topping Manipulator

Topping reduces the growing point at the top of cotton plants. This process enables the plant to allocate more energy and nutrients to fruit growth, thereby enhancing both the quantity and quality of the fruit. Current cotton-topping machinery often leads to over-topping, which can affect crop yield and quality. Manual topping is effective in controlling over-topping due to its adherence to agronomic requirements, but it is labor-intensive. This study integrated principles from biology (bionics) to design a manipulator that mimics the action of hand pinching during manual topping. Screening grids of different sizes were designed based on a statistical analysis of the biological parameters of cotton tops to optimize the topping process. A disc cam mechanism was developed to enable the automatic opening and closing of the manipulator. From the results, it was evident that the spring tension must exceed 81.5 N to properly cut the cotton stem near the top. The spacing of the screening grid (40 mm) and the position of the topping manipulator (less than 50 mm) were optimized based on experimental results. Performance testing showed promising results with a 100% topping rate. This study not only identified the challenges with current cotton-topping methods but also proposed a bionics-inspired solution; a bionic manipulator equipped with a screening grid was proposed to achieve high accuracy in cotton topping, which significantly reduced over-topping rates to 6.67%. These findings are crucial for advancing agricultural technology and improving efficiency in cotton cultivation.

Design of disk cam mechanisms with a translating follower having symmetrical double-concave faces

Design of disk cam mechanisms with a translating follower having symmetrical double-concave faces

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.

Comparison of recent optimization algorithms for design optimization of a cam-follower mechanism

This study presents the application of seven recent meta-heuristic optimization algorithms to automate design of disk cam mechanism with translating roller follower regarding four follower motion laws. The algorithms are: salp swarm algorithm (SSA), moth–flame optimization (MFO), ant lion optimizer (ALO), multi verse optimizer (MVO), grey wolf optimizer (GWO), evaporation rate water cycle algorithm (ER-WCA), and mine blast algorithm (MBA). The optimum cam design problem is formulated with three objectives including the minimum congestion, maximum performance, and maximum strength resistance of the cam. Moreover, the effect of selecting follower motion law on the optimal design of mechanism is investigated. The computational results clearly indicate that the utilized algorithms are very competitive in structural design optimization, especially MBA, ER-WCA, MFO and GWO techniques. Among the four follower motion laws, the polynomial 3-4-5 degree is the best one.

A method for modelling contact between circular and non-circular shapes with variable radii of curvature and its application in planar mechanical systems

Contact impact has been widely found in the operation of various mechanical systems. These mechanical systems include the type of mechanism typically characterised by circular–non-circular geometric contact. They consist of the mechanisms of the cam with a roller follower, a Geneva wheel with intermittent motion, a cog belt drive with circular-arc teeth, a cycloidal-pin wheel gear, and a roller chain drive. For the two components in contact, one component needs to have an ideal circular shape, while the other is characterised by its non-circular geometry, that is, the contact shape may present varying radii of curvature. Taking this kind of contact mechanical system as a research object, this work proposes a general method for analysing the problems concerning contact impact on this circular–non-circular geometry. This method discretises continuous non-circular geometries to acquire a series of discrete points. Then, the contact areas of components are determined by repeatedly judging the relationships between the positions for various discrete points and the circular geometric centres thereof. In the contact areas, the maximum depth of the contact is measured, and the positions of the contact points between components, in a direction along the maximum contact depth, are determined. Finally, the normal contact force and tangential friction force between contacting components are established at the contact points. This method can be applied to analyse the problems concerning single contact and multi-point contact among various contact components. To verify the validity of this method, this work takes an offset translational roller follower disc cam mechanism (with a single contact) and a cycloidal-pin wheel gear mechanism (with multi-point contact) as examples and investigates the dynamic characteristics of the contact impact for the aforementioned mechanical systems, respectively.

Design and analysis of high-speed cam mechanism using Fourier series

This study proposes an innovative and comprehensive method for the design and analysis of a high-speed cam mechanism. In the proposed method, the displacement function of the cam follower is described using Fourier series. The coefficients of the series are obtained by constraint equations during the cam rise period and the minimum principle of displacement error function (where, error function refers to the variance between actual displacement and ideal displacement of the cam follower during the dwell). The validity of the proposed design method is verified through a case study with focus on high-speed cam mechanism design. In the design case, kinematic characteristic analysis of this cam follower shows that the order of continuous derivative of displacement transfer function is higher, the characteristic value of its dynamic torque is smaller, and its jerk at the impact point is smaller than some common disc cam mechanisms. The results indicate that the proposed method can reduce the vibration of the cam mechanisms and its impact velocity is smaller than the existing design methods.

Size synthesis method for disc cam mechanisms with a negative radius translating roller follower

This work considers a disc cam mechanism with an upright installed negative radius translating roller follower. Accurate descriptions, as well as the basic concept and steps, are given for the shape, basic/overall size, and size synthesis of the new mechanism. A size coordinate system O − r0 R and size domain Ω( r0, R) are established, which are given discrete-meshing (grid) treatment. In addition, four constraints are proposed for the calculation formula. The traversal technique is used to achieve visual mapping under single/merged constraints, which gives the corresponding boundary and solution domain. Then, a combination of multiobjective planning and visual mapping reveals important principles such as the non-inferior region [Formula: see text], ridge point [Formula: see text]/ridge line ∂ [Formula: see text], and bottom ridge point P**/double optimal point [Formula: see text], as well as the existence of the global optimal solution. We have therefore obtained instructive and important conclusions for the size synthesis of the new mechanism.

Tolerance Analysis of Rotating Mechanism Based on Skin Model Shapes in Discrete Geometry

Geometric deviations are inevitably observable on every manufactured workpiece. These deviations affect the function and quality of mechanical products and have therefore to be controlled by geometric tolerances. Computer-aided tolerancing aims at supporting design, manufacturing, and inspection by determining and quantifying these effects of geometric deviations on the product quality and the functional behaviour. However, most established tolerance representation schemes imply abstractions of geometric deviations and are not conform with the standards for geometric dimensioning and tolerancing. These limitations led to the development of a Skin Model inspired framework for the tolerance analysis, which is based on a representation of non-ideal workpieces employing discrete geometry representation schemes, such as point clouds and surface meshes. In this contribution, this Skin Model inspired framework for computer aided tolerancing is extended to systems in motion and applied to the tolerance analysis of rotating mechanism with higher kinematic pairs. For this purpose, the generation of non-ideal part representatives, as well as their processing with algorithms for registration and computational geometry are highlighted. Finally, the results are visualized and interpreted. The procedure as well as the simulation model itself are shown in a case study of a disk cam mechanism.

Disk Cam Contour Design Based on Inventor 2009

Taking disk cam mechanism with translating follower as an example, this paper introduces a method of rapid parameter design for disk cam contour through motion simulation platform Inventor 2009, by which the cam entity can be produced in accuracy. The function of motion simulation of Inventor 2009 is fully used to check the design, so that the efficiency of product design could be greatly improved.

A Computational Approach for Cam Size Optimization of Disc Cam-Follower Mechanisms With Translating Roller Followers

The main objective of this work is to present a computational approach for design optimization of disc cam mechanisms with eccentric translating roller followers. For this purpose, the objective function defined here takes into account the three major parameters that influence the final cam size, namely, the base circle radius of the cam, the radius of the roller and the offset of the follower. Furthermore, geometric constraints related to the maximum pressure angle and minimum radius of curvature are included to ensure good working conditions of the system. Finally, an application example is presented and used to discuss the main assumptions and procedure adopted throughout this work.

Mechanical Analysis of Disc Cam Mechanisms with Negative Radius Roller Translating Follower

This paper proposes the conditions of no-undercutting and contact-retaining of the disc cam mechanism with negative radius roller follower. Then, it presents the contact stress expression based on the mechanical analysis. In addition, the effects of different parameters on the force and contact stress are analysed. The results show that the contact stress can be reduced by designing the suitable parameters of the cam.

Optimization Design of Disc Cam Mechanisms with an Offset Translating Negative Radius Roller Follower

The offset optimization is one of the key elements of designing cam mechanisms. This paper presents the mechanical model of a disc cam mechanism with an offset translating negative radius roller follower and deduces the efficiency expression. Then it proposes pressure angle and efficiency integration as the evaluation index of pressure angle and efficiency respectively. Furthermore, the optimal offset is derived according to the index. Finally, an example is provided to illustrate the method to obtaine the optimal offset.

Research on the General Second Mechanisms Synthesis Task of Disc Cam Mechanisms with Roller Follower Moving in General Planar Motion

To cam mechanisms with roller follower moving in general planar motion,the concepts of "special and general type II mechanisms synthesis tasks" are put forward,and the scientific and exact description is brought.Via establishment of coordinate system,introduction of "floating coordinate system" and division of front and rear work travel,especially the introductions of new concepts of "instantaneous choice area" and "whole choice area",the new graphic fundamental for solving "instantaneous choice area" of roller-center as well as deep analysis of boundary are brought out.The concepts of "most commercial search belt-area" and important thinking of eqisdistance-dispersion are given.Dimensionality-drop rapid solving algorithm is given,which satisfactorily solves "general type II mechanisms synthesis task".

Second Mechanisms Synthesis Task of Positive-drive Disc Cam Mechanisms with Roller Follower Moving in General Planar Motion

Positive-drive cam mechanisms are used in a great variety of applications and are of complexity and speciality in synthesis theory and methods.Based on the concepts "floating axis","instantaneous and whole nested interval" and introducing the new concepts "go and return travel","radius-marking line",It deeply and systematically researches the second mechanisms task of conjugate-cam,groove-cam and yoke radial cam with roller follower.Research results is as follow: not being simple combination and summation of force-drive cam mechanisms,the synthesis of positive-drive cam mechanisms is of complicated,deep,special and original research cultivation.Regarding the yoke radial cam with roller follower as sample,a series of research thought,research method and research conclusions are obtained.A mechanism synthesis example is displayed.

Design on Disc Cam Mechanism of Roller Follower

The requirements on the movement law of the follower imposed by disc cam mechanism of roller follower are considered, and the influencing factors of the relative motion between the roller and the cam contour are investigated. The requirements on the roller radius for the rolling motion of the roller that is relative to the cam contour are analyzed. It can be found that the constant speed movement, one of the common follower motion laws, cannot be applied alone to roller follower disc cam mechanism; otherwise movement distortion for the follower will happen. The movement distortion caused by inappropriate choice of the movement law can not be avoided by increasing cam base circle radius or by decreasing roller radius. There is a required minimum roller radius for the relative movement between the roller and the cam contour to be rolling movement. The minimum radius is inversely proportional to the rolling friction coefficient between the roller and the cam contour, proportional to the radius of the friction circle of the revolute pair between the roller and the follower lever, and independent of the load of the cam mechanism, pressure angle and other dimension parameters.

The Parametric Design and Motion Analysis of Disc Cam Mechanism with Straight Motion and Deviation Roller Follower

In view of those situations which follower of cam mechanism have complicated motion law in rise travel and return travel, basing on secondary development and applying synthetically of Pro/E, following the reverse turn principle of the tradition graphic method, the wholly parameterized design system was developed. Furthermore, virtual assembly and motion simulation had been realized. According to the parameter imported by the consumer, the system can generate automatically cam pitch curve and cam contour of 16 kinds of combination follower motion law. It can raise cam mechanism product design quality and efficiency.

Some Important Applications of Support-Function in Theory of Mechanisms

Via putting forward the new concept of “direction angle” for the first time, particularly via discovering and bringing to light the vivid, audio-visual geometrical background of integral geometry′concepts “support line” and “support function” in disc cam mechanisms with a flat-bottomed translating follower, this paper successfully obtains package formulae for judging the outward convexity of cam profile's, for calculating the equations and perimeter of cam profile’ as well as the area of cam end surface’.

Second Mechanism Synthesis Task of Disc Cam Mechanisms with Roller Follower Moving in Planar General Motion

Size synthesis about disc cam mechanisms with planar-general-motion roller follower are summarized as two kinds,then the accurate description of these mechanism synthesis tasks are concluded. The first mechanism synthesis task is solved by means of the concept of virtual oscillating follower. The universal thought,method and step of the second mechanism synthesis task are proposed by introducing a German high speed printing machine as an example. A set of analytical formulae of the determination of the instantaneous nested interval and the whole nested interval are proposed firstly by the coordinate establishment,the floating number axis and the division of work travel. The existence and its analytical criterion of these formulae are proposed,and then the method to determinate the allowable area for roller center and the value range of the cam's base circle radius are obtained. A mechanism synthesis example is displayed.

A COMPUTERIZED APPROACH FOR TOLERANCE ANALYSIS OF DISK CAM MECHANISMS WITH A FLAT-FACED FOLLOWER

A computerized approach for analyzing the tolerances in disk cam mechanisms with a flat-faced follower is presented in this paper. Based on the simulated higher-pair contact analysis, the kinematic deviation of the follower motion caused by the tolerance amount of each design parameter can be determined numerically. The method is validated by means of analyzing the case of an eccentric circular cam mechanism; such a case has an exact solution of the follower motion error. Compared with the exact solutions, the presented computerized approach is demonstrated to be able to provide excellent accuracy and sufficient efficiency no matter how large the level of the tolerance is. Then, both the offset translating oblique flat-faced follower and the oscillating flat-faced follower cases are given to illustrate the presented method. The presented computerized approach and the obtained results can be helpful for tolerance allocation tasks of disk cam mechanisms with a flat-faced follower.

Disk cam mechanisms with a translating follower having symmetrical double rollers

This paper proposes a novel translating follower that has symmetrical double rollers and also demonstrates how to design such a cam mechanism. Two identical rollers are symmetrically mounted on opposite sides of the follower. The two rollers will take turns to contact the cam when the cam rotates. The application of this follower can greatly reduce the pressure angle on both the rising and the falling motions of the follower. It may also reduce the induced forces.