Modeling of Optimal Screw Jack Design
R.Senthilkumar, Mechanical Engineering,
Krishnaswamy college of Engineering,
Annamalainagar,Tamilnadu 1thermalsenthil@gmail.com
1P.Ramesh, P.Velmurugan, Mechanical Engineering, Annamalai University, Cuddalore, Tamilnadu, 2erprlme_2000@yahoo.co.in
23Abstract- The aim of this paper is modeling of optimal screw jack design using VBA Programming in AutoCAD package software. Today’s demand grows need of good design and quality product with short span of time to achieve a better product. The software development in the digital world is a vital role to satisfy a number of demands, in this regard author considers CAD software to develop design of screw jack. The application software having the instruction as per the developer but it not meets the user. When the user handles that software, they need a long time span to complete a 3D modeling with complicated design. In AutoCAD, the programming languages are embedded through macros to design our needs as programming language. They are lisp programming, Auto lisp programming, dialogue control language programming and visual basic programming. In this paper design of screw jack using visual Basic aide programming language embedded with AutoCAD is developed. The Visual Basic language software is user friendly and it is windows application. The development of dialogue boxes and coding for the designs are very easy to debugging than the other language in AutoCAD. Basically, the design of 3D modeling carries a huge space to save the process and also inconvenient to transfer from one system to another system configuration. The programming language occupy little space and also easy to transfer via a small memory disc to other system configuration. The development of modeling 2d design and other parameter are easy to explore simultaneously through dialogue boxes of proposed software. This software having the code to do for optimization of screw jack modeling when click required command buttons in the dialogue box. The step by step of the statement in this software is executed to process the parameter. If anyone of the parameter is not satisfy, it will carry out the optimization without knowledge of user to produce exact design parameters and give good design. In future this kind of software development helps the researchers and scholars to get quick and precision design or any data.
Keywords-Macros; VBA; Form designer; Modules; Design; Optimization and Modelling.
I. INTRODUCTION
A very important repair tool in the automobile industry is the vehicle jack. Essentially the jack is used in raising a vehicle sufficiently above the ground to remove tyres when required. A vehicle owner without a jack will, at an unguarded moment, suffer loss in time, finance and energy. Although the vehicle jack does not contribute directly to the smooth running of a vehicle engine, yet its availability is crucial during tyre deflation. There are two broad types of vehicle jack that can be obtained in practice, viz. the mechanical
jackscrew
type and the hydraulic type. The mechanical jack can be of the scissors type or of a simple screw jack. When the scissors jack is placed in position under a vehicle, the rotation of the handle causes the frame to rise, thus producing a lift of the vehicle. When it is not in use (unload condition), the handle isgiven reverse rotation, which collapses the frame and makes it compact enough for packaging. For a simple screw jack in operation, two gearwheels are meshed so that their shafts are at an angle of 90o to form a bevel gear. One gearwheel locates the handle while the other contains an internal thread in its bone that meshes with the load screw. By rotation of the handle, the driving gearwheel is rotated and this is transmitted to the driven gearwheel, which also induces a lift of the load arm and consequently a lift of the vehicle. The second type of the vehicle jack, the hydraulic type, has its lift provided by hydraulic fluid forced against the load head by a reciprocating motion of the handle. This jack has a higher mechanical advantage compared to mechanical jacks.
An advantage of jackscrews over some other types of jack is that they are self-locking, which means when the rotational force on the screw is removed, it will remain motionless where it was left and will not rotate backwards, regardless of how much load it is supporting. This makes them inherently safer than hydraulic jacks, for example, which will move backwards under load if the force on the hydraulic actuator is accidentally released.
A jackscrew's threads must support heavy loads. In the most heavy-duty applications, such as screw jacks, a square thread or buttress thread is used, because it has the lowest friction. In other application such as actuators, an Acme thread is used, although it has higher friction.
The large area of sliding contact between the screw threads means jackscrews have high friction and low efficiency as power transmission linkages, around 30%–50%. So they are not often used for continuous transmission of high power, but more often in intermittent positioning applications.
The Ball screw is a more advanced type of leadscrew that uses a recirculating-ball nut to minimize friction and prolong the life of the screw threads. The thread profile of such screws is approximately semicircular (commonly a \to this type of screw is that it is not self-locking.
Jackscrews form vital components in equipment. For instance, the failure of a jackscrew on a McDonnell Douglas MD80 airliner due to a lack of grease resulted in the crash of Alaska Airlines Flight 261 off the coast of California in 2000.
3D modeling
In 3D computer graphics, 3D modeling is the process of developing a mathematical representation of any three-dimensional surface of object (either inanimate or living) via specialized software. The product is called a 3D model. It can be displayed as a two-dimensional image through a process called 3D rendering or used in a computer simulation of physical phenomena. The model can also be physically created using 3D
printing devices.
Models may be created automatically or manually. The manual modeling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting.
3D models represent a 3D object using a collection of points in 3D space, connected by various geometric entities such as triangles, lines, curved surfaces, etc. Being a collection of data (points and other information), 3D models can be created by hand, algorithmically (procedural modeling), or scanned.
3D models are widely used anywhere in 3D graphics. Actually, their use predates the widespread use of 3D graphics on personal computers. Many computer games used pre-rendered images of 3D models as sprites before computers could render them in real-time.
Today, 3D models are used in a wide variety of fields. The medical industry uses detailed models of organs. The movie industry uses them as characters and objects for animated and real-life motion pictures. The video game industry uses them as assets for computer and video games. The science sector uses them as highly detailed models of chemical compounds. The architecture industry uses them to demonstrate proposed buildings and landscapes through Software Architectural Models. The engineering community uses them as designs of new devices, vehicles and structures as well as a host of other uses. In recent decades the earth science community has started to construct 3D geological models as a standard practice.
The integration of computers into the product design and development process has benefited engineering industry in several ways.
The computer can store and handle engineering data accurately and consistently in the various stages of design, development and manufacturing like conceptual design of systems, analysis, component design, documentation, process planning & manufacturing. The computer aided design and computer aided manufacturing results in better and consistently good quality products invariably at a lower cost, with the attendant benefits of faster development of different variants of the product or model. CAD helps the designer to quickly visualize the product and its component subassemblies and parts. This reduces the time required to synthesize, analyse and document the design. The result is not only lower design cost but also shorter product development times. Design errors are reduced by the in-built accuracy of calculations and checks available in the system. These factors lead to improvement in the quality and accuracy of design.
II. IMPLEMENTATION OF CAD
AutoCAD has evolved from DOS – Based, command – line driven program to a full – fledged windows application. A computer aided design package used for drafting of Engineering, Civil, and Electrical drawings. AutoCAD is one of the successful application programs. Learning AutoCAD means learning the speed, ease with which your drawings can be prepared and modified using a particular program in the computer. The most important factor involved in this computer to store many programs or drawings, to editing the existing drawing, to backup the drawings with other device like Floppy Diskette, Compact
Disc, etc., and handle large amount of Engineering data. AutoCAD offers a comprehensive selection of 2D & 3D drawings. The various design – related tasks which are performed by a modern computer-aided design system can be grouped into four functional areas:
1. Geometric modeling 2. Engineering analysis 3. Design review and evaluation 4. Automated drafting
These four areas correspond to the final phases in Shigley’s general design process. Engineering analysis corresponds to phase 4, dealing with analysis and optimization . Design review and evaluation is the fifth step in the general design procedure. Automated drafting involves a procedure for converting the design image data residing in computer memory into a hard-copy document. It represents and important method for presentation (phase 6) of the design. The following four sections explore each of these four CAD functions.
III. VISUAL BASIC APPLICATION
Microsoft VBA is an object-oriented programming environment designed to provide rich development capabilities similar to those of Visual Basic (VB). The main difference between VBA and VB is that VBA runs in the same process space as AutoCAD, providing an AutoCAD intelligent and very fast programming environment. There are four advantages to implementing VBA for AutoCAD: ?The Visual Basic programming environment is easy to learn and use.
?VBA runs in-process with AutoCAD. This translates to very fast program execution.
? Dialogue construction is quick and effective. This allows developers to prototype applications and
quickly receive feedback on designs.
? Projects can be stand alone or imbedded in drawings. This choice allows developers great flexibility
in the distribution of their applications. A. Macros Dialogue Box
The Macros dialogue box allows to run, delete, and create new macros, and provides access to the VBA project options. B. VBA Manager
The VBA Manager allows to manage the projects. It can create, delete, embed, or extract projects. Also view which projects, if any, are embedded in an open drawing. C. Vbaide
The VBA Interactive Development Environment. This application allows you to edit the code and forms in the project, or copy code and forms from other projects. It also allows to set references to other