A Numerical Contour Method for Simulating Spiral Groove Bottom Profiles

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Weifeng Wu ◽  
Shuo Sun ◽  
Quanke Feng
Keyword(s):  
Surface Profile ◽  
Contour Method ◽  
Contact Lines ◽  
Spiral Groove ◽  
Groove Surface ◽  
Contact Points ◽  
Envelope Method ◽  
Twin Screw ◽  
Rotor Profiles ◽  
Boundary Contact

The envelope method can be used to model the spiral groove surface profile in single screw compressors produced by cylindrical milling using the contact lines of the cutter surface and the groove. However, the envelope method cannot predict the groove bottom profile accurately because it does not account for the boundary contact lines on the end face of the cutter. A new numerical contour method is proposed to model the groove bottom profile by identifying the contact points on the end face of the cutter to a set position on the spiral groove. Results show that the new method can calculate accurately both the boundary and the inner contact line and thus simulate the groove bottom profile exactly. This method could also be used to simulate other profiles of machines, such as rotor profiles of twin screw compressors and screw pumps.

Synthesis and Optimization for Rotor Profiles in Twin Rotor Screw Compressors

1998 ◽  
Vol 122 (4) ◽  
pp. 543-552 ◽  
Author(s):  
Shyh-Haur Su ◽  
Ching-Huan Tseng
Keyword(s):  
Contact Line ◽  
Optimization Problems ◽  
Synthesis Method ◽  
Line Length ◽  
Contact Lines ◽  
Rotor Profile ◽  
Twin Screw ◽  
Screw Rotor ◽  
Rotor Profiles ◽  
Parameter Values

This paper proposes a systematic synthesis method for twin-screw rotor profiles for compressors. Both “original generating curves” and “generated curves” are distributed on each rotor profile, and all the geometric parameters of these curves can be determined with satisfying the conditions of continuity in tangency by given only several specific parameter values. The contact lines on rotor surfaces and the blowhole area calculation are also presented. Three cases of optimization problems are shown in this paper and both contact-line length and blowhole area are reduced when letting the contact-line length be the object function with a constraint of blowhole area. [S1050-0472(00)01103-X]

Real-Time 2D Surface Profile Mapping of Biological Tissue with Force Feedback in Robot-Assisted Minimally Invasive Surgery

2015 ◽  
Vol 798 ◽  
pp. 319-323
Author(s):  
Ali Reza Hassan Beiglou ◽  
Javad Dargahi
Keyword(s):  
Minimally Invasive Surgery ◽  
Minimally Invasive ◽  
Real Time ◽  
Invasive Surgery ◽  
Strain Gauge ◽  
Force Feedback ◽  
Surface Profile ◽  
Robot Assisted ◽  
Contact Points ◽  
Force Signal

It has been more than 20 years that robot-assisted minimally invasive surgery (RMIS) has brought remarkable accuracy and dexterity for surgeons along with the decreasing trauma for the patients. In this paper a novel method of the tissue’s surface profile mapping is proposed. The tissue surface profile plays an important role for material identification during RMIS. It is shown how by integrating the force feedback into robot controller the surface profile of the tissue can be obtained with force feedback scanning. The experiment setup includes a 5 degree of freedoms (DOFs) robot which is equipped with a strain-gauge ball caster as the force feedback. Robot joint encoders signals and the captured force signal of the strain-gauge are transferred to developed surface transformation algorithm (STA). The real-time geometrical transformation process is triggered with force signal to identify contact points between the ball caster and the artificial tissue. The 2D surface profile of tissue will be mapped based on these contact points. Real-time capability of the proposed system is evaluated experimentally for the artifical tissues in a designed test rig.

Bridge Surface Roughness Identified from the Displacement Influence Lines of the Contact Points by Two Connected Vehicles

2020 ◽  
pp. 2043003
Author(s):  
Y. B. Yang ◽  
B. Q. Wang ◽  
Z. L. Wang ◽  
K. Shi ◽  
H. Xu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Surface Roughness ◽  
Dynamic Properties ◽  
Surface Profile ◽  
Connected Vehicles ◽  
The Finite Element Method ◽  
Contact Points ◽  
Continuous Beams ◽  
Static Correlation ◽  
The Impact

In this study, a new, effective procedure is proposed for identifying the surface roughness from the responses recorded of two connected test vehicles moving over the bridge. Central to this study is the proposal of a simple static correlation formula for relating the dynamic deflections of the two vehicles’s contact points on the bridge, via the displacement influence lines (DILs). With the aid of this relation, the roughness formula for estimating the bridge surface profile is derived using the responses of the leading and following vehicles. It does not require any prior knowledge of the dynamic properties of the bridge. The efficacy of the proposed procedure is validated for both the simple and three-span continuous beams by the finite element method (FEM). Also, a parametric study is conducted for various physical properties of the test vehicles. It is confirmed that the roughness profiles back-calculated from the proposed formula agree excellently with the assumed ones for both the simple and continuous beams. For use in practice, the two connected test vehicles should not be designed too heavy and not to move at too fast speeds, in order to reduce the impact on the bridge.

Analytic and Experimental Study of the Load Distribution on Spline Joints Length Considering the Contact Rigidity of the Bearing Surfaces

2012 ◽  
Vol 162 ◽  
pp. 74-83 ◽  
Author(s):  
Dan Mărgineanu ◽  
E. Mărgineanu ◽  
E.S. Zăbavă ◽  
A. M. Fârtă
Keyword(s):  
Experimental Study ◽  
Mechanical System ◽  
Elastic Properties ◽  
Load Distribution ◽  
Degrees Of Freedom ◽  
Surface Profile ◽  
Contact Rigidity ◽  
Contact Points ◽  
Actual Load ◽  
Contact Surfaces

The spline joints transmit torque from shafts to rotors by multiple contact surfaces. The joint's mechanical system is, therefore, undetermined, i.e. the number of contact points is much larger than the number of restricted degrees of freedom. Thus, the actual load distribution is greatly influenced by the joints elements elastic properties and their geometrical errors and surface profile. In this paper, an analytical and experimental study for the load distribution on the in joints length caused by the finite rigidity of the joints elements is presented.

An experimental and numerical study of the expansion forming of a thick-walled microgroove tube

2008 ◽  
Vol 223 (3) ◽  
pp. 689-697 ◽  
Author(s):  
D Tang ◽  
Y Peng ◽  
D Li
Keyword(s):  
Mechanical Performance ◽  
Numerical Study ◽  
Surface Profile ◽  
Processing Parameters ◽  
Forming Process ◽  
Axial Section ◽  
Die Geometry ◽  
Contact Points ◽  
Industrial Sectors ◽  
Full Contact

CO2 refrigerant-based air conditioning and refrigeration (ACR) is an increasing concern in many industrial sectors for its zero ozone depletion potential. One of the major requirements in its application is the forming technology of thick-walled tube according to the extremely high pressure working conditions of the ACR system. This article presents a study on the expansion process joining the thick-walled microgroove copper tube to aluminium fins. Experiments of the forming process have been carried out. Finite-element models are developed to investigate the deformation of overall and local structures. Evaluation of the joining quality along the longitude axis of the tube is first attempted. The agreement of the results on the contact surface profile confirms that the joint is far away from full contact in the axial section. Formation mechanism of the unexpected contact status lies in displacement of the contact points along the section of the fin collar, which is mainly related to the expanding ratio. To improve the forming quality, discussion on processing parameters and die geometry is conducted. Results show that the expanding ratio is the major factor influencing the thermal—mechanical performance of the joint and 2–6 per cent can be the comprehensively beneficial range for a thick-walled ACR tube; average contact pressure can reach 1.76 Mpa under proper set. The results are helpful for improving the energy efficiency ratio performance of the natural refrigerant-based system.

scholarly journals A geometric study of different curves for the rotor profiles of a twin-screw compressor

2021 ◽  
Vol 312 ◽  
pp. 11001
Author(s):  
Antonio Giuffrida
Keyword(s):  
Straight Line Segment ◽  
Base Case ◽  
Conic Sections ◽  
Current Case ◽  
Rotor Profile ◽  
Straight Line ◽  
Twin Screw ◽  
Rotor Profiles ◽  
Geometric Study

This paper presents the results of comparisons among some patented solutions for profiling the contours of the rotors in twin-screw compressors. Referring to a base case where all the generating curves are circumferences, patents suggesting to replace arcs of circumference with arcs of conic sections, i.e. parabola, ellipse and hyperbola, but even a straight line segment, are presented and guidelines for rotor profile construction are reported. After setting the size of the compressor, attention is paid to the inter-lobe area, as the sum of the area between two consecutive lobes in the male rotor and of the area of the groove in the female rotor. Actually, this area is strictly related to the volume displacement. Limited to the current case study, the profile including an elliptic segment seems to be the preferable solution for higher inter-lobe area, then for higher displacement, though a number of considerations should be necessary for a broader context.

Evaluating the Interlobe Clearance and Determining the Sizes and Shapes of All the Leakage Paths for Twin-Screw Vacuum Pump

2006 ◽  
Vol 220 (4) ◽  
pp. 499-506 ◽  
Author(s):  
Z H Fong ◽  
F C Huang
Keyword(s):  
Cross Section ◽  
Vacuum Pump ◽  
Contact Pattern ◽  
Minimum Cross Section ◽  
Exact Evaluation ◽  
Twin Screw ◽  
Red Lead ◽  
Rotor Profiles ◽  
Screw Rotors ◽  
Cross Section Method

The maximum sphere method and the minimum cross-section method are proposed to calculate the interlobe clearance between two mating screw rotors and to determine the shapes and sizes of all the leakage paths. These two methods are inspired by the red-lead and tooth-contact pattern and can be used to evaluate the interlobe leakage and to design the mating rotor profiles. The combined results of these two methods provide the basis for an exact evaluation of the fluid leakage, and this feature increases flexibility in geometrical designing and manufacturing of the screw rotors. These methods are also suitable for non-conjugate rotors and contribute to thermal analysis and optimum programming.

Screw Rotor Profiles of Variable Lead Vacuum and Multiphase Machines and Their Calculation Models

2016 ◽  
Author(s):  
Nikola Stosic ◽  
Sham Rane ◽  
Ahmed Kovacevic ◽  
Ian K. Smith
Keyword(s):  
Manufacturing Cost ◽  
Twin Screw ◽  
Wrap Angle ◽  
Screw Rotor ◽  
Rotor Profiles ◽  
Calculation Models ◽  
Moving Parts

Twin screw machines are mechanically simple and reliable, having only two moving parts, while their manufacturing cost is low and, as a result of optimization of their rotor proportions and profiles, their efficiency is high. Consequently, they are now used widely both as multiphase and vacuum pumps. This study gives the results of an investigation of how their performance is affected by changing the rotor lead, i.e. the axial step along the rotor wrap, from a constant value to a variable one. A number of different configurations have been considered and it is shown that, for machines with a large wrap angle, a variable lead results in greater displacement and improved efficiency.

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