Tie Neng Guo

The Study of High Strength Bolt Preload with Hydraulic Tensioner Installation

Preloading the high strength bolt using hydraulic extension method is a fast and efficient method for bolt installation. Hydraulic bolt tension device can guarantee the initial tension of bolt well. However, if the relation of initial tension and the final remaining preload of bolt cannot be determined, the preload on the bolts still cannot be guaranteed. This paper uses theoretical analysis method to research the relation between the eventual preload and the initial tension of high strength bolts on Heavy-duty Gantry beams. Then we proposes a set of calculation method of bolt installation preload and the initial tension and provides theoretical basis for the installation of heavy-duty segmented beam.

Simulation Analysis and Experiment Research for a Large Span and Heavy Load Crossbeam

Aiming at solving issues of load bearing deformation compensation and sympathetic vibration, this paper takes a large span and heavy load crossbeam of a domestic heavy-type numerical control milling planer for research object, the final purpose is to improve machining precision and stability of the heavy machine tool product. The load curve considering the influence of columns deformation, natural frequency and vibration model are obtained, respectively by the dynamic and static simulation analysis of the crossbeam with the finite element analysis method. Then, the modal analysis results are verified through the model experiment. Lastly, this paper presents an approach by estimating the load curve to improve machining precision, points out the weak links, and provides guidance for crossbeam structure design, optimization and reverse manufacture.

The Deformation Analysis about Guide Way Contact of Large Span and Heavy Load Cross-Rail

The article used the large span and heavy load cross-rail of some machine tools plant’s heavy-type numerical control milling planer for research object, by using the finite element software to build the model and force analysis. It also researched the force distribution and deformation condition of the large span motion girder under the actual working condition. It considered the slide carriage superposition effect to build the describing method and establishing process of the large span load curve by contacting analysis and restraining analysis, and got the knifepoint trajectory deformation. The research provided the sufficient theory basis and simulation method for designing improvement of cross-rail structure and got a perfect arch in advance.

The Nonlinear Vibration Characteristics of Gear Swing System of Overload Swing Angle Milling Head

The overloaded swing angle milling head is an important part of the CNC machine tools; the swing system is the drive components of overloaded swing angle milling head for feed movement, mainly by gears for cutting the feed motion. In this paper, a multi-degree-of-freedom nonlinear dynamic model with multi-level multi-backlash spur gears was established, by using of numerical analysis method to solve the analysis of gears wing nonlinear vibration characteristics of the system, the results show that the gaps between the gears have a rich nonlinear characteristics of the vibration of the system.

Experimental Analysis of the Nonlinear Normal Static Stiffness of Bolted Joints

The normal static stiffness plays an important role in the whole connection of bolted joints. Both the design and the connection quality are depended on the normal static stiffness. But the nonlinear characteristics of its normal static stiffness is not well explained. An experimental test is developed herein to clarify the influence of the jointed surfaces. And the nonlinear effect of jointed surfaces of bolted members has been separated from the total stiffness. The nonlinear relation between the extensile force and the joints’ stiffness in the jointed surfaces under different preloads has been extracted through the experiment.

Identification of the Dynamic Properties of Mechanical Joints

The frequency response functions (FRFs) are frequently used to identify dynamic properties of the mechanical joints. However, the ill-posed problems of the system are caused by the contamination of measurement noise even if it is processed by reduction technique. In order to solve this problem, put the noised FRFs into identification equations to theoretical derivation, explained the degree of influence on the identified results by noised FRFs in theory. In order to make the identified results represent real properties of the joints, an improved FRFs method was developed based on subtraction term frequency selection, in which the measured data were processed could get high degree of anti-noise frequency before parameters identification. This method avoids the occurrence of ill-posed problems. The results of simulation show that the proposed method can solve the ill-posed problems, thus significantly improve the accuracy of identification.

Study on Modeling Method and Characteristics of Bearing System with High Rotation Speed

This paper established a general mathematical modeling method based on stress analysis of the angular contact ball bearing under high rotation speed. The influence of the centrifugal force and gyroscopic moment generated in the rotation process is taken into account in this mathematical model. This paper conducted in-depth research for these aspects: the stiffness characteristics of angular contact ball bearings under different load conditions and different rotational speed, internal contact deformation and the change of bearing parameters.

A General Method for the Modeling of Bearing Systems

Based on force analysis of angular contact ball bearings, this paper proposes a generic mathematical modeling method. This paper conducts in-depth research for these aspects: all directions of the stiffness characteristics under different load conditions of angular contact ball bearings, internal contact deformation and the change of bearing parameters. This article eventually gets the variation of the bearing characteristics under different load conditions.

Analytical Modeling of the Spindle Shaft of Heavy Load Deflection Angle Milling Head Dynamics Using Timoshenko Beam Model

The spindle shaft of heavy load deflection angle milling head is an important functional component of 5-axis CNC machine tool, which has characteristics of high torque and high power, used for large and complex free-form surface processing. The spindle shaft is modeled as Timoshenko’s beam by including the centrifugal force and gyroscopic effects. The effects on inherent characteristic of the spindle shaft of heavy load deflection angle milling head are analyzed owing to axial force and spindle shaft speed. Simultaneously, numerical solution of spindle shaft is gotten. And, the numerical results are well agree with the exact modeling, which illustrates that the theoretical modeling of spindle shaft is correct and the exact dynamic characteristics of spindle shaft is obtained. The analytical modeling results of spindle shaft are effective and helpful for design and improvement of spindle shaft of heavy load deflection angle milling head.

Modeling Method of Assembled Structure Coupling the Characteristics of the Joints

Mechanical properties of the joints have impacted on the whole mechanical characteristics. Coupling the joint characteristics in the modeling of the machine tool is an important problem in machine mechanics analysis. In order to solve the joint modellings in the assembled structure, this paper presents a new method to creat beam elements between two symmetrical nodes on the contact surface of the joint. The stiffness and damping matrices of the elements are valuated according to the characteristics of the joint. To validate the accuracy of the proposed method, the modeling of an assembled structure with and without the joints is obtained and some corresponding experimental investigations are implemented. The error between the simulated and experimental results of the finite element model is less than 8.8%, while the error of the contact model often used in the existing literatures is one times bigger than the proposed model.