Analysis and Synthesis of Conical Coil Springs

2021 ◽  
Author(s):  
Harshkumar Patel ◽  
Hong Zhou
Keyword(s):  
Coil Spring ◽  
Spring Rate ◽  
Helical Springs ◽  
Compression Spring ◽  
Spring Wire ◽  
Coil Diameter ◽  
Constant Pitch ◽  
Analysis And Synthesis ◽  
Compression Springs ◽  
Mechanical Devices

Abstract Springs are mechanical devices that are employed to resist forces, store energy, absorb shocks, mitigate vibrations, or maintain parts contacting each other. Spring wires are commonly coiled in the forms of helixes for either extension or compression. Helical springs usually have cylindrical shapes that have constant coil diameter, constant pitch and constant spring rate. Unlike conventional cylindrical coil springs, the coil diameter of conically coiled springs is variable. They have conical or tapered shapes that have a large coil diameter at the base and a small coil diameter at the top. The variable coil diameter enables conical coil springs generate desired load deflection relationships, have high lateral stability and low buckling liability. In addition, conical compression springs can have significantly larger compression or shorter compressed height than conventional helical compression springs. The compressed height of a conical compression spring can reach its limit that is the diameter of the spring wire if it is properly synthesized. The height of an undeformed conical coil spring can have its height of its spring wire if the spring pitch is chosen to be zero. The variable coil diameter of conical coil springs provides them with unique feature, but also raises their synthesis difficulties. Synthesizing conical coil springs that require large spring compression or small deformed spring height or constant spring rate is challenging. This research is motivated by surmounting the current challenges facing conical coil springs. In this research, independent parameters are introduced to control the diameter and pitch of a conical coil spring. Different conical coil springs are modeled. Their performances are simulated using the created models. The deflection-force relationships of conical coil springs are analyzed. The results from this research provide useful guidelines for developing conical coil springs.

Synthesis of Concave Helical Compression Springs

2015 ◽  
Author(s):  
Naresh Kumar Gandham ◽  
Hong Zhou
Keyword(s):  
Cylindrical Shape ◽  
Control Parameters ◽  
Spline Curve ◽  
Variable Diameter ◽  
Compression Spring ◽  
Spring Wire ◽  
Coil Diameter ◽  
Constant Pitch ◽  
The Common ◽  
Compression Springs

Helical compression springs are used to resist compressive forces or store energy in push mode. They are found in many applications that include automotive, aerospace and medical devices. The common configuration of helical compression springs is straight cylindrical shape that has constant coil diameter, constant pitch and constant spring rate. Unlike cylindrical helical compression springs, concave helical compression springs have a larger diameter at each end and a smaller diameter in the middle of the spring. The variable coil diameter enables them to produce desired load deflection characteristics, reduce solid height, buckling and surging, and keep them centered on a larger diameter hole. The unique features of concave helical compression springs also raise their synthesis challenges. In this paper, a method is introduced to synthesize concave helical compression springs. The variable coil diameter of a concave helical compression spring is described by a spline curve. A cylinder with variable diameter is generated by revolving the spline curve on spring axis. The concave helical compression spring is then modeled by wrapping a spring wire on the variable diameter cylinder. The synthesis of a concave helical compression spring is systemized as the optimization of the geometric control parameters of its wrapped spring wire. A synthesis example is presented in the paper to verify the effectiveness and demonstrate the procedure of the introduced method.

scholarly journals Improved analytical model for cylindrical compression springs not ground considering end behavior of end coils

2021 ◽  
Vol 22 ◽  
pp. 50
Author(s):  
Guillaume Cadet ◽  
Manuel Paredes ◽  
Hervé Orcière
Keyword(s):  
Length Relationship ◽  
Analytical Simulation ◽  
Linear Load ◽  
Compression Spring ◽  
Constant Pitch ◽  
Linear Behaviour ◽  
Experimental Approaches ◽  
Linear Force ◽  
Force Components ◽  
Compression Springs

In a context of increased competition, companies are looking to optimize all the components of their systems. They use compression springs with constant pitch for their linear force/length relationship. However, it appears that the classic formula determining the global load-length of the spring is not always accurate enough. It does not consider the effects of the spring's ends, which can induce non-linear behaviour at the beginning of compression and thus propagate an error over the full load-length estimated. The paper investigates the entire behaviour of a cylindrical compression spring, not ground, using analytical, simulation and experimental approaches in order to help engineers design compression springs with greater accuracy. It is built with an analytical finite element method, considering all the geometry and force components of the spring. As a result, the global load-length of compression springs can be calculated with more accuracy. Moreover, it is now possible to determine the effective tri-linear load-length relation of compression springs not ground and thus to enlarge the operating range commonly defined by standards. This study is the first that enables the behaviour to be calculated quickly, by saving time on dimensioning optimisation and on the manufacturing process of compression springs not ground.

Effect of the galvanization process on the fatigue life of high strength steel compression springs

2021 ◽  
Vol 63 (3) ◽  
pp. 226-230
Author(s):  
Fatih Özen ◽  
Ahmet İlhan ◽  
Hakkı Taner Sezan ◽  
Erdinç İlhan ◽  
Salim Aslanlar
Keyword(s):  
Fatigue Life ◽  
Hydrogen Embrittlement ◽  
High Strength Steel ◽  
Reaction Force ◽  
Fatigue Crack Initiation ◽  
High Strength ◽  
Steel Wires ◽  
Compression Spring ◽  
Spring Wire ◽  
Compression Springs

Abstract In this study, a compression spring fatigue problem arising from the galvanization process was investigated. Fatigue, crack initiation and growth of galvanized and non-galvanized springs manufactured from fully pearlitic high strength steel wires were investigated. According to the results, the galvanized compression springs exhibited a low fatigue life due to hydrogen embrittlement. Hydrogen embrittlement induced crack initiations formed under the galvanizing layer and adversely affect fatigue life. It was observed that local embrittlement on the outer surface of the spring wire causes crack initiations and disperses through the pearlitic interlamellar microstructure. Compared to non-galvanized and shot-peened specimens with the same surface roughness, compression springs, galvanized compression springs exhibited a 25 % reaction force loss at 50 000 cycles.

scholarly journals Stability of Physically-Loaded Helical Springs used in Smart Fork Lift

2019 ◽  
Vol 9 (2) ◽  
pp. 3839-3845
Keyword(s):  
Heat Treatment ◽  
Spring Steel ◽  
Original Form ◽  
Helical Spring ◽  
Storage Devices ◽  
Helical Springs ◽  
Conical Shape ◽  
Steel Material ◽  
Compression Springs ◽  
Mechanical Devices

In the following section, the behavior of helical compression springs is considered in smart fork lift (established in previous work). We have used commonly used cylindrical and conical shape helical spring as storage devices in which stability defined in term of load-gains, deflections and evaluation of spring-rates. Springs’ rates of both springs were compared on a common platform. Initially both springs (helical-conical) was prepared from the coiled wires. These prepared springs also known as coil springs which regain its original form and position when distorted by the loaded in smart fork-lift apparatus. These coils springs here developed by the applying the heat treatment and quenching processes on the galvanized spring steel material by using the threaded shape fixtures. This prescribed work focused on effect of physically-loaded gains by cylindrical and conical shaped helical spring in smart fork lift. Here, springs worked as mechanical devices to bear the lifting load which differed here greatly in strength and in size depending on changing its parameters. Both the cylindrical and conical shape was made of helically coiled wires with constant clearance between the active coils and able to absorbed external counteracting loads applied against each other in their axis. One direction deformation in axially format was considered.

Effect of the Material Types on the Fundamental Frequencies of Uniaxial Composite Conical Springs

1999 ◽  
Author(s):  
Vebil Yildirim ◽  
Erol Sancaktar ◽  
Erhan Kiral
Keyword(s):  
Transfer Matrix Method ◽  
Pitch Angle ◽  
Natural Frequencies ◽  
Axial Deformation ◽  
Helical Springs ◽  
Fundamental Frequencies ◽  
Helix Pitch ◽  
Constant Pitch ◽  
Α Helix

Abstract This paper deals with the effect of the material types (Graphite-Epoxies and Kevlar-Epoxy) on the fundamental frequencies of uniaxial constant-pitch composite conical helical springs with solid circle section and fixed-fixed ends. The transfer matrix method is used for the determination of the fundamental natural frequencies. The rotary inertia, the shear and axial deformation effects are taken into account in the solution. The free vibrational charts for each material presented in this study cover the following vibrational parameters: n (number of active turns) = 5–10, α = (helix pitch angle) = 5° and 25°, R2/R1, (minimum to maximum radii of the cylinder) = 0.1 and 0.9, and Dmax/d (maximum cylinder to wire diameters) = 5 and 15. These charts can be used for the design of uniaxial composite conical springs.

scholarly journals Numerical Assessment of a One-Mass Spring-Based Electromagnetic Energy Harvester on a Vibrating Object

2016 ◽  
Vol 41 (1) ◽  
pp. 119-131 ◽  
Author(s):  
Min-Chie Chiu ◽  
Ying-Chun Chang ◽  
Long-Jyi Yeh ◽  
Chiu-Hung Chung
Keyword(s):  
Optimal Design ◽  
Energy Harvester ◽  
Damping Ratio ◽  
Electrical Power ◽  
Electromagnetic Energy ◽  
Design Parameters ◽  
Helical Springs ◽  
Spring Wire ◽  
Excitation Period ◽  
Mass Spring

Abstract The paper is an exploration of the optimal design parameters of a space-constrained electromagnetic vibration-based generator. An electromagnetic energy harvester is composed of a coiled polyoxymethylen circular shell, a cylindrical NdFeB magnet, and a pair of helical springs. The magnet is vertically confined between the helical springs that serve as a vibrator. The electrical power connected to the coil is actuated when the energy harvester is vibrated by an external force causing the vibrator to periodically move through the coil. The primary factors of the electrical power generated from the energy harvester include a magnet, a spring, a coil, an excited frequency, an excited amplitude, and a design space. In order to obtain maximal electrical power during the excitation period, it is necessary to set the system’s natural frequency equal to the external forcing frequency. There are ten design factors of the energy harvester including the magnet diameter (Dm), the magnet height (Hm), the system damping ratio (ζsys), the spring diameter (Ds), the diameter of the spring wire (ds), the spring length (ℓs), the pitch of the spring (ps), the spring’s number of revolutions (Ns), the coil diameter (Dc), the diameter of the coil wire (dc), and the coil’s number of revolutions (Nc). Because of the mutual effects of the above factors, searching for the appropriate design parameters within a constrained space is complicated. Concerning their geometric allocation, the above ten design parameters are reduced to four (Dm, Hm, ζsys, and Nc). In order to search for optimal electrical power, the objective function of the electrical power is maximized by adjusting the four design parameters (Dm, Hm, ζsys, and Nc) via the simulated annealing method. Consequently, the optimal design parameters of Dm, Hm, ζsys, and Nc that produce maximum electrical power for an electromagnetic energy harvester are found.

Fundamental Frequencies of Uniaxial Composite Barrel and Hyperboloidal Springs

1999 ◽  
Author(s):  
Vebil Yildirim ◽  
Erol Sancaktar ◽  
Erhan Kiral
Keyword(s):  
Free Vibration ◽  
Transfer Matrix ◽  
Shear Deformation Theory ◽  
Variable Coefficients ◽  
Axial Deformation ◽  
Circular Section ◽  
First Order ◽  
Helical Springs ◽  
Fundamental Frequencies ◽  
Constant Pitch

Abstract The fundamental natural frequencies of uniaxial composite non-cylindrical helical springs (barrel and hyperboloidal types) are determined theoretically based on the transfer matrix method. The rotary inertia, shear and axial deformation effects are considered with the first order shear deformation theory. The overall transfer matrix is obtained by integrating the twelve scalar ordinary differential equations with variable coefficients governing the free vibration behavior of non-cylindrical helical springs made of an anisotropic material. Numerical results are verified with the reported values for isotropic non-cylindrical helices. A parametric study is performed to investigate the effects of the number of active coils (n = 5–0), the helix pitch angle (α = 5° and 25°), the ratio of the minimum to maximum cylinder radii (Rmin/Rmax), and the ratio of the maximum cylinder diameter to the wire diameter (Dmax/d) on the fundamental free vibration frequencies of constant-pitch composite barrel and hyperboloidal helical springs with circular section and fixed-fixed ends.

Design, Modeling and Fabrication of Micro-Robotic Actuators With Ionic Polymeric Gel and SMA Micro-Muscles

1995 ◽  
Author(s):  
Mohsen Shahinpoor ◽  
Martin W. J. Burmeister ◽  
Wesley Hoffman
Keyword(s):  
Electric Field ◽  
Fiber Bundle ◽  
Size Range ◽  
Fiber Bundles ◽  
Polymer Gel ◽  
Polymeric Gel ◽  
Compression Spring ◽  
Micron Size ◽  
End Caps ◽  
Compression Springs

Abstract Presented are the details for design and fabrication of a novel micro-robotic actuator in a few micron-size range. The model is in the form of contractile fiber bundles embedded in or around micron size helical compression springs. The fiber bundle is assumed to consist of a parallel array of contractile fibers made form either electrically or chemically (pH muscles) contractile ionic polymeric muscles such as polyacrylic acid plus sodium acrylate cross-linked with bisacrylamide (PAAM) or polyacrylonitrile (PAN) fibers or electrically contractile shape-memory alloy (SMA) fiber bundles. The proposed model considers the electrically or pH-induced contraction of the ionic polymeric fibers as well as resistive heating of the SMA fiber bundles in case of shape-memory alloys. A theoretical model is also presented for the dynamic modeling of such micron size robotic actuators. These robotic micro-actuators will open a new frontier to the micro-universes of biological, scientific, medical and engineering systems. On the fabrication side, helical compression springs and bellows in a few microns size range have been manufactured in our laboratories to serve as the main resilient structure for the micro-robotic actuator. In principle, any size micro-robotic linear actuator can be fabricated and tested in our laboratory. For the case of ionic polymeric gel fibers the model consists of an encapsulated hermetically sealed, helical compression spring-loaded cylindrical linear actuators containing a counterionic solution or electrolyte such as water+acetone, a cylindrical helical compression micro-spring and a collection of polymeric gel fibers (polyelectrolytes) such as polyvinyl alcohol (PVA) polyacrylic acid (PAA) or polyacrylamide. Furthermore, the helical micro-spring not only acts as a compression spring between the two hermetically sealed circular end-caps but contains snugly the polymeric gel fiber bundle and also acts as the cathode (anode) electrode -while the two actuator end-caps act as the other cathode (anode) electrodes. In this fashion, a DC electric field of a few volts per centimeter per gram of polymer gel can cause the polymer gel fiber bundle to contract (expand). This causes the compression spring to contract and pull the two end-caps closer to each other against the elastic resistance of the helical spring. By reversing the action by means of reversing the electric field polarities the gel is allowed to expand while the compression spring is also expanding and helping the linear expansion of the actuator since the polymeric gel muscle expands due to the induced alkalinity along the helical spring body. Thus, electrical control of the expansion and the contraction of the micro-robotic linear actuator is possible. A mathematical model is presented based on the proposed composite structure that takes into account all pertinent variables such as the pH of the gel fiber bundle, the pH of the surrounding medium, the hyperelastic parameters of the fiber bundle, the electrical variables of the gel, the electric field strength, the pH field strength and all pertinent dimensions followed by some numerical and experimental simulations and data. For the second model, we consider the fiber bundle of SMA to be either circumscribed inside a micron size helical compression spring with flat heads or in parallel with a number helical compression springs, end-capped by two parallel circular plates with embedded electrodes to which the ends of the SMA fibers are secured. Thus, the fibers can be electrically heated and subsequently contracted to compress the helical compression spring back and forth. Design details are first described. In essence the dynamic behavior of the actuator depends on the interaction between the current supplied to the wires and the heat transfer from the wires. Further, a mathematical model is presented to simulate the electro-thermo-mechanics of motion of such actuators. The proposed model takes into account all pertinent variables such as the strain ϵ, the temperature of the fibers T(t) as a function of time t, the ambient temperature T0, the martensite fraction ξ, the helical compression spring constant k and the overall heat transfer coefficient h. Numerical simulations are then carried out and the results are compared with experimental observations of a number of fabricated systems in a size range of a few mcrons.

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