Factors affecting the torsional frequency response of machine tool drive systems

1972 ◽  
Vol 12 (1) ◽  
pp. 65-83 ◽  
Author(s):  
W.A. Knight
Keyword(s):  
Machine Tool ◽  
Frequency Response ◽  
Factors Affecting ◽  
Torsional Frequency ◽  
Drive Systems

Determination of Machine Tool Frequency Response Function During Cutting

2004 ◽  
Author(s):  
Emmanuil Kushnir
Keyword(s):  
Steady State ◽  
Machine Tool ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Dynamic Compliance ◽  
Cutting Conditions ◽  
Machine Tool Structure ◽  
Different Types ◽  
External Sources

The dynamic compliance (frequency response function - FRF) of a machine tool structure in the cutting zone under a cutting load is one of the major dynamic characteristics that define a machine’s cutting performance. The roundness and surface finish define the quality of the manufactured parts. These characteristics are developed during finishing and semi-finishing cuts. The kinowledge of machine tool dynamic compliance, defined in these steady-state cutting conditions, ensures parts quality and increase in machine tool productivity. The dynamic compliance is usually evaluated in tests, which are performed by means of hammers or vibrators (exciters). During these tests the machine does not cut and the machine components do not move relative to each other. The loads in the machine during cutting are defined by different internal and external sources that are acting in different points of the machine and in different directions. The real spectrum and frequency range of these forces is unknown. Experimental data acquired by different types of tests clearly show the difference in dynamic compliance for the same machine tool during cutting and idling. The machine tool dynamic tests performed by different types of external exciting devices do not take in consideration the real load conditions and interactions of moving components, including the cutting process itself and external sources of vibration. The existing methods of experimental evaluation of machine tool dynamic compliance during steady-state cutting condition require dynamometers to measure the cutting force and a special sensor to measure relative displacement between the cutting tool and workpiece. The FRF that is computed from these measurements represents a dynamic characteristic of the close loop system (machine structure and cutting process) and only under certain conditions may be considered as FRF of machine tool structure itself. The theory of stationary random processes allows defining the cutting conditions, under which the obtained data represent the FRF of machine tool structure, and provide estimations of random and bias errors of this evaluation. The simplified methodology of FRF estimation, based only on measurement of the spindle and tool vibration, is also presented in this paper. This methodology is used on an assembly line to obtain FRF for machine tools performance comparison and quality assurance.

Dynamic Stability of a Motorized High Speed Machine Tool Spindle Supported on Bearings

2014 ◽  
Vol 612 ◽  
pp. 29-34
Author(s):  
Jakeer Hussain Shaik ◽  
J. Srinivas
Keyword(s):  
Machine Tool ◽  
Frequency Response ◽  
High Speed ◽  
Stability Boundary ◽  
Second Phase ◽  
Element Formulation ◽  
Machining Parameters ◽  
Response Functions ◽  
Frequency Response Functions ◽  
The Stability

Dynamic behaviour of spindle system influences chatter stability of machine tool considerably. Self-excited vibrations of the tool results in unstable cutting process which leads to the chatter on the work surface and it reduces the productivity. In this paper, a system of coupled spindle bearing system is employed by considering the angular contact ball bearing forces on stability of machining. Using Timoshenko beam element formulation, the spindle unit is analyzed by including the gyroscopic and centrifugal terms. Frequency response functions at the tool-tip are obtained from the dynamic spindle model. In the second phase, solid model of the system is developed and its dynamic response is obtained from three dimensional finite element analysis. The works on analysis of the stability of milling processes focus on calculating the stability boundary of the machining parameters based on the dynamic models characterizing the milling processes. The stability lobe diagrams are generated from frequency response functions (FRF’s) lead to an stability limit prediction for the system at high speed ranges.

scholarly journals High Performance Rotary Table for Machine Tool Applications

2009 ◽  
Vol 3 (3) ◽  
pp. 343-347 ◽  
Author(s):  
K. M. Muditha Dassanayake ◽  
◽  
Masaomi Tsutsumi ◽  
Keyword(s):  
Machine Tool ◽  
Frequency Response ◽  
High Performance ◽  
Worm Gear ◽  
Rotary Table ◽  
Positioning Accuracy ◽  
Roller Drive ◽  
Gear Mechanism ◽  
Accuracy And Repeatability

The high performance rotary tables are immense necessary part for the multi-axis machines. These rotary tables are yet in the developing stage. In this report, a rotary table driven by roller drive is introduced and the characteristics of that are discussed by comparing them with the characteristics of rotary table driven by worm gear mechanism. As the characteristics, the positioning accuracy and repeatability, frequency response, rotational fluctuations and influence of unbalance mass on motion are measured. According to the measured results, it can be said that the rotary table driven by roller drive shows high performances and therefore it can be said that this type of rotary tables are well suited for machine tool applications.

Ploughing-Pulling Forming for Wicking Structure of Flat Micro-Groove Heat Pipe and Machine Tool Optimization

2020 ◽  
Vol 36 (4) ◽  
pp. 423-435
Author(s):  
Xibing Li ◽  
Zhixiong Ye ◽  
Nanpeng Li ◽  
Jialun Chen ◽  
Tengyue Zou
Keyword(s):  
Machine Tool ◽  
Heat Pipe ◽  
Sharp Increase ◽  
Processing Parameters ◽  
Machining Process ◽  
Forming Process ◽  
Factors Affecting ◽  
Strength Limit ◽  
Forming Methods ◽  
Tool Optimization

ABSTRACTIn forming procedure of the micro grooves in the flat micro-groove heat pipe, the tie rod is often observed to be broken and the multi-tooth cutter is damaged due to the sharp increase of the ploughing-pulling pressure. This paper theoretically analyzes the factors affecting the capillary heat transferring limit of the micro-groove heat pipe, and simulates the machining process using finite element to acquire the best processing parameters: the squeeze angle is 120°, the drawing depth is 0.25mm, and the ploughing-pulling velocity is 100mm/s. Then these parameters are verified by real manufacturing experiments. The experimental results show that the ploughing-pulling pressure of the micro-groove forming process is close to the strength limit of the rod or multi-tooth cutter, and the process makes little swarf during work. Thus, only using the appropriate machine tool parameters, forming parameters and forming methods can make the wicking structure of flat micro-groove micro-heat pipe with the best heat transferring performance.

Study on Method to Avoid Chatter Vibration Based on Machine Tool Rigidity

2020 ◽  
Author(s):  
Akio Hayashi ◽  
Hiroto Ishibashi ◽  
Yoshitaka Morimoto ◽  
Yoshiyuki Kaneko ◽  
Naohiko Suzuki
Keyword(s):  
Machine Tool ◽  
Frequency Response ◽  
Frequency Response Function ◽  
Stability Limit ◽  
Cutting Conditions ◽  
Machining Accuracy ◽  
Stable Limit ◽  
Chatter Vibration ◽  
The Stability ◽  
The Relationship

Abstract Chatter vibration decreases machining accuracy and thus presents a problem in manufacturing. In order to eliminate chatter vibration based on the estimation of stable cutting conditions from a stability limit diagram and to determine the cutting conditions accordingly has been proposed. However, changing the cutting conditions may lead to a decrease in productivity. The stability limit is estimated from the relationship between machine rigidity and the cutting conditions. In the present study, we proposed a system to avoid chatter vibration by changing the rigidity of the machine tool. We developed the desktop machine tool that can change its rigidity by varying the preload of a brace bar attached to the frame. In order to clarify the relationship between the chatter vibration and the rigidity of the desktop machine tool, the stability limit of the desktop machine tool was determined by conducting machining tests and comparing the results with a simulated stable limit diagram. We then investigated the frequency response function within the simulation. The results showed that the transition of the stability limit can be accomplished by changing the rigidity of the desktop machine tool, and indicate that chatter vibration can be avoided by simulation.

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