COMPARATIVE STRUCTURAL ANALYSIS OF ACME AND SQUARE THREAD SCREW JACK

A screw jack is a device used to lift the vehicle above the ground level in order to ease repairs. A power screw is designed to translate radial motion to linear motion. Many users are familiar with manually operated car jack which still included as standard equipment in cars. A car jack is an important device in vehicle to change flat tire in our journey. Every year near about 160 injuries are associated with car jacks. The correct use of jacks can prevent the accidents and injuries. Improvement in Design of car jack is really important to make the tool more efficient and user friendly with high safety features. The objectives of this project work is to critically analyze and compare between ACME and SQUARE threads from stress and strain perspective in order to improve the performance from safety and durability point of view for developments in the field of thread design. In this project selection of two different types of screw threads namely Square and Acme threads. The square threads are named after their square geometry. They are the most efficient power screw, but also the most difficult to machine, thus most expensive. The Acme threads are machining with multipoint cutting tool on thread milling machine, it is an economical operation. Acme threads have more thickness at core diameter than of Square threads therefore a screw with Acme threads is stronger than equivalent screw with Square threads. Assumptions made in designing a Power screw are the total load is distributed among the threads i.e. of car jack of capacity 1.5 to 3 tones threads are in direct shear, various stresses in screw like tensile or compressive in the body of the screw due to an axial load. Thus, the different type of screw threads is designed as per the dimensions, experimental calculations and analyzed using Abaqus FEA software. Model developed is to be validated using experimental and analysis calculatio