An experiment on the shape and depth of air pocket on air spindle vibrations in ultra precision machine tools

Abstract

In order to achieve nanometer accuracies, low vibration in air spindle is vital. Some parameters affecting air spindle vibration could be mentioned as rotational speed, inlet hole diameter, air pocket geometry, air gap pressure and so on. In this study, the air pocket geometry and depth plus rotational speed are experimentally investigated. Three levels of quantity are selected for each parameter. Vibration movements were considered as experiment output. Then, experimental results were analyzed by design of experiment method. The results showed that the air spindle with an air pocket of rectangular shape and 3 mm depth at low rotational speed has minimum vibrations.

Dynamics characteristics of a rotary table motorized spindle with externally pressurized air bearings

“…(3) is mounted on the test stand (4). The spring-loaded method [14] consists of the upper load-applying block (6), the lower load-applying block (9), the load-applying bolt (1), the guide bar (2), and the spring (7). The test force is measured by the force sensor (8), and the axial displacement Δ of spindle top due to the air film deformation is measured by the micrometer (5).…”

“…Compared with the rolling bearing spindle, the fluid spindle [7,8] has higher loading capacity, higher rotation accuracy and longer working life, but more complicated construction and higher manufacture cost. Among three rotary tables, the air bearing spindle [9][10][11] is highest in the rotation accuracy, lowest in friction loss, lowest in heat generation and longest in working life. Despite of being less favorable in loading capacity, the air bearing spindle can also be used to carry a large load by increasing the diameter and decreasing the clearance of the bearing.…”

Measurement and analysis for frequency domain error of ultra-precision spindle in a flycutting machine tool

“…Besides, Xiang et al 20 accurately predicted multi-degree-of-freedom spindle thermal errors by applying experimental modifications to preliminary theoretical models of the temperature field and thermal deformation. Akhondzadeh and Vahdati 21 investigated the influence of air pocket geometry and depth on air spindle vibrations through the experiment.…”

Air pocket effects on air spindle vibrations in nanomachining

“…In previous researches, except those by Akhondzadeh and Vahdati, 14,15 the air pocket parameters that have been selected for analysis were air bearing stiffness, load capacity, and flow rate, whereas air bearing vibrations have not been investigated. In the present study, the air pocket parameters such as shape, size, depth, number, and shaft rotational speed have been selected for investigating the air spindle radial vibrations.…”

“…In the present study, the air pocket parameters such as shape, size, depth, number, and shaft rotational speed have been selected for investigating the air spindle radial vibrations. In Akhondzadeh and Vahdati, 14,15 the effects of these parameters have been investigated separately: in one study, 14 the effects of size and number of air pockets have been studied and in the other, 15 the shape and depth have been analyzed.…”