High-speed sliding-inchworm motion mechanism with expansion-type pneumatic hollow-shaft actuators for in-pipe inspections

Mechatronics ◽  
2018 ◽  
Vol 56 ◽  
pp. 101-114 ◽  
Author(s):  
Tomonari Yamamoto ◽  
Masashi Konyo ◽  
Kenjiro Tadakuma ◽  
Satoshi Tadokoro
Keyword(s):  
High Speed ◽  
Motion Mechanism ◽  
Hollow Shaft

scholarly journals Study on High-Speed Intermittent Motion Mechanism. Comparison Indexing Cam Mechanism with Servo-System.

2002 ◽  
Vol 68 (668) ◽  
pp. 1191-1197
Author(s):  
Masatoshi HIKIZU ◽  
Hiroaki SEKI ◽  
Yoshitsugu KAMIYA ◽  
Hiroshi TACHIYA ◽  
Hisanao NOMURA
Keyword(s):  
High Speed ◽  
Servo System ◽  
Motion Mechanism ◽  
Cam Mechanism ◽  
Intermittent Motion

DYNAMIC ANALYSIS OF A ROTARY HOLLOW SHAFT WITH HOT-FIT PART USING CONTACT ELEMENTS WITH FRICTION

2011 ◽  
Vol 35 (3) ◽  
pp. 461-474 ◽  
Author(s):  
Shin-Yong Chen ◽  
Chieh Kung ◽  
Jung-Chun Hsu
Keyword(s):  
Natural Frequency ◽  
Contact Stress ◽  
High Speed ◽  
Modal Testing ◽  
Key Factors ◽  
Normal Contact Stress ◽  
Normal Contact ◽  
Hollow Shaft ◽  
Testing Experiment ◽  
Local Stiffness

One of the key factors in designing a motor built-in high speed spindle is to assemble the motor rotor and shaft by means of hot-fit. Presented in this paper is a study of the influence of a hot-fit rotor on the local stiffness of the hollow shaft. Dynamic analyses of the rotor-hollow shaft assembly using contact elements are conducted. The normal contact stress state between the rotor and the hollow shaft is obtained through the use of contact elements with friction effects included. The normal contact stress, considered as the pr-stress between the rotor and the hollow shaft, is then adopted for subsequent modal analyses. In this study, the modal analysis results are verified by a modal testing experiment. The percent errors of the first natural frequency and the second natural frequency are down to about 0.58% and 0.79%, respectively.

Parametric Studies on Dynamic Performance of Hydrostatic Flexure Pivot Tilting Pad Gas Bearing With Radial Compliance

2007 ◽  
Author(s):  
Robert N. Petro ◽  
Daejong Kim
Keyword(s):  
High Speed ◽  
Heat Dissipation ◽  
Optimal Choice ◽  
Hollow Shaft ◽  
Bearing Clearance ◽  
Radial Stiffness ◽  
Hybrid Operation ◽  
Tilting Pad ◽  
Rotor Bearing ◽  
Gas Bearing

Flexure pivot tilting pad gas bearings are recognized as an alternative to foil gas bearing [1, 2] for high speed turbomachinery, due to their capability to provide high rotor-bearing stability and simple structure. The flexure pivot design eliminates wear problem of axial pins or sockets at the pivots which are common in traditional tilting pad bearings. Added features such as a pivot offset and pad preloads can also be optimized to further improve the stability. Hybrid flexure pivot tilting pad gas bearing have also been reported [3]. The hybrid bearing has a direct air supply to the bearing clearance through a tiny orifice. It has shown that the hybrid operation of the tilting pad gas bearing can also increase the rotor-bearing stability [3]. In many microturbomachinery applications, hollow shafts are adopted to reduce the rotor weight and increase the bending critical speeds. However, the hollow shaft has a large centrifugal growth at high speeds requiring the gas bearing to have radial compliances. However, the radial compliance within the tilting pads can compromise the rotor-bearing stability because large displacement of the pads along the radial direction can cause hydrodynamic rotor-bearing instability associated with the increased bearing clearance (i.e. decreased effective preload) if the radial stiffness is not designed properly. Analytical studies show that optimal choice of pad radial stiffness could extend operating envelope of flexure pivot tilting pad gas bearing without deteriorating rotor-bearing stability [4]. High speed operation can generate significant amount of heat and adequate heat dissipation mechanism should also be developed. Hybrid operation is considered to have added benefit of effective cooling capability. This paper presents design studies on hybrid flexure tilting pad gas bearing with radial compliance which can accommodate large rotor centrifugal growth and also provide effective cooling mechanism.

Research on the Status and Prospect of the Hollow Shafts Forming Technology in High-Speed Train

2012 ◽  
Vol 201-202 ◽  
pp. 1071-1075
Author(s):  
Shu Hua Zheng ◽  
Wen Fei Peng ◽  
Xue Dao Shu
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Lightweight Construction ◽  
Cross Wedge Rolling ◽  
Heavy Load ◽  
Hollow Shaft ◽  
Forming Technology ◽  
The Status ◽  
New Type ◽  
Hollow Shafts

High-speed and heavy-load are the targets to pursue over a long period of time in high-speed transportation. The key to solve this problem is making the components lightweight. Particularly, the hollow shaft is a new type of lightweight construction. This article explains systematically the current situation and the defects of forming technique for the hollow shafts. The solid shafts formed by Multi-Wedge Cross Wedge Rolling (MCWR) and the hollow shafts by Cross Wedge Rolling(CWR) are researched, and the key problems of hollow shafts formed in MCWR to solve emphatically are pointed out. At the same time, we obtain that MCWR will be the main technology in forming long shafts. The results in this paper provide a new direction for the hollow shafts to form in a high efficiency, energy saving and material saving method.

THE DYNAMIC ANALYSES AND VERIFICATIONS OF A HOLLOW SHAFT WITH HOT-FIT COMPONENT USING 3D FINITE CONTACT ELEMENT

2013 ◽  
Vol 37 (1) ◽  
pp. 21-38 ◽  
Author(s):  
Shin-Yong Chen
Keyword(s):  
Stress State ◽  
High Speed ◽  
Contact Element ◽  
Modal Testing ◽  
Engineering Practice ◽  
Stressed Condition ◽  
Theoretical Formulation ◽  
Hollow Shaft ◽  
Rotor Shaft ◽  
Key Factor

In general engineering practice, one key factor in designing a motor built-in high-speed spindle is to assemble the motor rotor and shaft by means of hot-fit to form a new rotor-shaft assembly. In this paper, the dynamic analysis of a hot-fit rotor in a rotor-shaft assembly by using 3D contact element is proposed. Contact pressure between the rotor and the shaft is firstly calculated through contact theory. The stress state is thus determined. The finite element modal analysis then follows with the stress state as a pre-stressed condition. The accuracy and the validity of the finite contact element results are verified by theoretical formulation, equivalent static analysis and experimental modal testing. The results presented herein indicate that it is accurate and effective in analyzing the dynamic behavior of the rotary shaft system with a hot-fit component by using contact element.

Thermal Performance Measurement of a Bump Type Gas Foil Bearing Floating on a Hollow Shaft for Increasing Rotating Speed and Static Load

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Tae Ho Kim ◽  
Jin Woo Song ◽  
Yong-Bok Lee ◽  
Kyuho Sim
Keyword(s):  
Outer Surface ◽  
High Speed ◽  
Static Load ◽  
Thermal Characteristics ◽  
Operating Conditions ◽  
Successful Implementation ◽  
Outer Diameter ◽  
Left Edge ◽  
Static Loads ◽  
Hollow Shaft

Identifying thermal characteristics of gas foil bearings (GFBs) provides an insight for successful implementation into high speed oil-free turbomachinery. The paper presents temperature measurements of a bump type GFB floating on a hollow shaft for various operating conditions. Two angular ball bearings support the hollow shaft at one end (right), and the other end (left) is free. Test GFB has the outer diameter of 100 mm and the axial length of 45 mm, and the hollow shaft has the outer and inner diameters of 60 mm and 40 mm, respectively. An electric motor drives the hollow shaft using a spline coupling connection. A mechanical loading device provides static loads on test GFB upward via a metal wire, and a strain gauge type load cell placed in the middle of the wire indicates the applied loads. During experiments for shaft speeds of 5 krpm, 10 krpm, and 15 krpm and with static loads of 58.9 N (6 kgf), 78.5 N (8 kgf), and 98.1 N (10 kgf), twelve thermocouples measure the outer surface temperatures of test GFB at four angular locations of 45 deg, 135 deg, 215 deg, and 315 deg, with an origin at the top foil free end, and three axial locations of bearing centerline and both side edges at each angle. Two infrared thermometers measure the outer surface temperature of the hollow shaft at free and supported ends close to test GFB. Test results show that GFB temperatures increase as the shaft speed increases and as the static load increases, with higher temperatures in the loaded zone (135 deg and 215 deg) than those in the unloaded zone (45 deg and 315 deg). In general, the recorded temperatures are highest at 225 deg where a highest hydrodynamic pressure is expected to build up. Measured temperatures at the bearing centerline are higher than those at the side edges, as expected. In addition, large thermal gradients are recorded in the hollow shaft along the axial direction with higher temperatures at the supported end. The axial thermal gradient of the shaft is thought to cause higher temperatures at the bearing right edge facing the ball bearing support than those at the left edge. The paper presents test data along with detailed test GFB/shaft geometries and material properties.

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