Simulating the Effect of Friction on Drive Screw Using System-of-System Modeling with Predetermined Torque

In most mechanical systems, screw threads serve three main basic purposes: (i) to transmit power, (ii) to provide a clamping force, and finally (iii) to restrict or control motion. This chapter demonstrates the effects of friction and behavior which can occur in a bolted fastening (screw thread) for advanced design purposes. To model this behavior, other control components are attached to the bolted screw. The bolt preload is applied with a predetermined torque. For this case the preload depends on the friction under the head and in the thread. The friction prevents the loosing of the bolted fastening. This effect is termed as self-locking effect. We designed an algorithm that reproduces an exemplary simulation scenario, which determines friction and its effect on thread angle based on the strength of the coefficient of friction at a specific tension or clamp load value using the system-of-system approach. The result shows specific behavior on both the motion in threads and drive screw with predetermined torque. The chapter is limited to creating a simple simulation environment to demonstrate the effects.

DESIGN AUTOMATION OF GEAR REDUCING BOX OF THE SURFACE DRIVE SCREW PUMP

The article discusses several types of surface drives of a screw pump. A method for automating the calculation of the main parameters of gear оf a gearbox is proposed. An example of the automated calculation system is given.

Research on Modeling and Simulation of the Trafficability of Vertical Screw Conveyors Intermediate Support Based on EDEM

Vertical screw conveyor is a kind of main equipments of bulk handing and delivery, and the intermediate support structure is one of the key parts of this equipment. It is necessary to make a research on it for improving the design and optimization to improve bulk delivery efficiency. Degree of freedom theory, analysis software of EDEM with discrete element and setting periodic boundary model are applied in this paper to simulate the vertical screw conveyors grain (rice) delivery process under different intermediate support structure. The results show that traditional intermediate support structure is three times statically indeterminate structure, while the degrees of freedom of new intermediate support is 1; The vertical screw transmission capacity of new type of vertical screw axis machine which uses intermediate spokes structure is slightly decreased, and the driving power required to drive screw axis increases slightly at the same time. The materials axial transport speed is not affected, but the requirement is greatly reduced for the manufacture and installation accuracy.

A Study on Gear Tooth Metal Flowing Law and Process Optimization of Spiral Bevel Gear Forging

Insufficient gear tooth corner filling and high forming load are the main problems in spiral bevel gear forging. In this study, three different preforms were proposed. According to the analysis of the forging spiral bevel gear process using the semi-closed die, which was based on elastoplastic finite element model, the metal flowing law of tooth along tooth alignment and profile are revealed. From the simulation results, the arc face shape preform and the finish die with divided flow cavity are good for forging gear, and an optimized process was presented. Experiments were carried out using electric drive screw press with the rated forming load of 2500 Tons. By analyzing numerical simulations and experimental results, the process mentioned in this paper improves the tooth corner filling and reduces the forming load effectively.

The Longitudinal Vibration Analysis of the Drive Screw Under the Elastic Supports

The ball screw drive system is obtained widespread application in the modern machine. Along with the improving of feeding velocity and working precision, its dynamic analysis becomes more and more important. Considering the bearing stiffness and the contact deformation between the worktable and the screw, the drive screw is seen as a bar under elastic supports at both ends and with an internal moving elastic support. Using boundary conditions and matching conditions, the longitudinal vibration frequency equation of the screw is derived and the mode shape of the screw is solved. The vibration frequency is analyzed when the worktable moves from the left to the right end of the screw. The effect of the system parameters on the natural frequency and the mode shape are studied to supply a base for designing the drive system.

The Lateral Vibration Analysis of the Machine Drive Screw

The drive screw is simplified as a rotating Tinoshenko beam under the pre-tension force. Using boundary conditions and continuity conditions, the frequency equation of the screw with the elastic supports is derived considering the effect of gyroscope, the pre-tension force, the bearing stiffness, and the contact between the worktable and the screw. The effect of the system parameters on the lateral natural frequency is studied to supply a base for designing the drive system.

Research on Fracturing Mechanism of Ground-Drive Screw Pump Polish Rod

In addition to vertical pulling force, the ground-drive screw pump oil recovery rod also stands twisting moment and bending moment. The diameter of the polish rod is generally larger than that of the pumping rod, and it stands a bit less stress than the pumping rod close to it, and the polish rod is generally made of relatively better materials. In practice, however, the polish rod fractures more often than the pumping rod above. This thesis considers that if the driving head deflects, the upper and the lower polish rods of the packing set are not in the same axial line, and bending moment will come into being in the polish rod of the lower part of the packing set due to the restriction of the polish rod by the packing set. Alternating stress caused by bending moment yields fatigue rupture of the polish rod during its rotation. This verdict is confirmed by the fracture position, the shape of the fractured surface, and quantitative calculation. This thesis proposes strict controlling of the deflection of the driving head by means of polish rod verticality survey instrument. Both theory and practice have proved that this method can effectively avoid fatigue rupture of the polish rod.