Analytical derivation of thread profile in internal thread milling process

Thread milling is a new machining process as compared to thread tapping. As a thread making process in use for a long time, thread tapping did not have any alternative processes except the thread turning for limited cases until computer numerical control (CNC) technology had enabled the three axes synchronized motion. Therefore, investigations about the thread milling process are less as compared to other machining processes. In this work, the thread profile in the internal thread milling process was derived analytically. Experimental work was also performed to verify the performance of the analytical model. It was revealed that the thread profile produced by the cutting edge of the tool is not a straight line but a curve, and the average slope through the thread profile is less than the slope of the cutting edge of the tool. Besides, the effective thread profile enlarges along the vertical axis and constricts laterally as the ratio of thread mill diameter to thread diameter increases.

Integrated Design of Spindle Speed Modulation and Cutting Vibration Suppression Controls Using Disturbance Observer for Thread Milling

In thread milling, there exists a trade-off between thread manufacturing efficiency and thread quality. In this study, an integrated design of spindle speed modulation (SSM) and cutting vibration suppression (CVS) controls using a disturbance observer were developed to simultaneously ensure superior quality and high manufacturing efficiency. The proposed integrated design not only controls the cutting torque while suppressing cutting vibrations but also ensures cost-effectiveness and mitigates the installation problems prevalent in existing sensor-based methods. The SSM control uses a disturbance observer to estimate the cutting torque required on the spindle during thread milling. The estimated cutting torque is used as a feedback signal so that the SSM control can modulate the spindle speed to make the cutting torque achieve a preset torque command. To further avoid cutting vibrations in thread milling, the CVS control analyzes the estimated cutting torque, detects the occurrence of cutting vibrations, and then adjusts the torque command of the SSM control to suppress the cutting vibrations. In this study, thread milling experiments were performed on a computer numerical control milling machine using the workpiece with stacked materials. The feasibility and performance of the proposed integrated design were validated by experiments.

Comparative structural Analysis of Acme and Square thread Screw jack using Autodesk Inventor

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 paper 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 paper 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.